I'm certain it could happen to you- to me- to any of us. The players are doing the clever thing, sneaking up on the encampment or outpost or what-have-you, and scouting ahead before the attack. Or perhaps you want to give your monsters a little flavor. Or you've decided that Talking Is a Free Action (look out, TV Tropes!) and that your monsters can roast players in the middle of combat as well. Anyway, here's some 'voice-lines' for a few of your monsters, as well as random stuff for them to be doing.

Please note: 'he' and 'she' are used interchangeably with regard to the adventurers.

Goblins.

Voice lines - idle.

"Remember, adventurers can't see you if you aren't carrying any coins, so just give 'em to me and I'll keep 'em safe."

"Hey, who's on dish-washing today?"

"Hmm...what do you think of this? The nose is a little weird, right?"

"Hey, finish up on the grindstone. Gotta sharpen my razor."

"Do you even know how to use a spear? You couldn't kill a rat in a mug like that!"

Voice lines - combat.

Ally wounded mildly. "Get 'im! Get 'im! It's just a scratch, hit 'im back!"

Ally wounded severely. "Oh Maglubiyet. Oh Maglubiyet. His arm's gone. Oh, Maglubiyet."

Ally killed. "You've killed my brother for the last time!"

Enemy Arcane caster present. "That's not normal!"

Enemy Barbarian rages. "Get oUTTA THE WAY!"

Enemy Paladin smites. "Oh, I get it. Maglubiyet hates us now."

Enemy Divine caster present. "Don't you bring religion into this! Get that jerk!"

Enemy Rogue Sneak Attacks. "Where'd that one come from? Get reinforcements!"

Idle animations.

Washing dishes.

Shooting at a bullseye target.

Whittling.

Panning gold in a river.

Sharpening weapons.

Arguing over chores roster.

Hobgoblins.

Voice lines - idle.

"Twenty-one! Twenty-two! Twenty-three!"

"Arms up, arms up. Hook, then jab, like this, see?"

"So it was my second tour, right? And the mud was up to my knees, mosquitoes everywhere..."

"Hang on. We'll pick this up later, gotta take patrol."

"Hey, Doc! Is Firebug back on his feet? We need a guy with a sense of humor around here."

"Rations at my old base were better, y'know..."

Voice lines - battle.

Ally wounded mildly. "Fight through it!"

Ally wounded severely. "Medic!"

Ally killed. "Friendly KIA! Stay sharp!"

Enemy Arcane caster present. "Keep an eye on the mage."

Enemy Divine caster present. "War priest on the field, say your prayers and get in close."

Enemy Paladin smites. "Extremist on the field, say your prayers and hit from afar."

Enemy Barbarian rages. "He's freakin' out, keep back!"

Enemy Rogue sneak attacks. "We've been flanked!"

Enemy killed. "EKIA!"

Enemy knocked unconscious or prone. "Out of the action, let's press the attack!"

Multiple attacks fail to hit enemy (heavy armor). "Enemy Juggernaut on the field, focus fire!"

Multiple attacks fail to hit enemy (light armor). "Slippery little- get back here!"

Idle animations.

Doing pushups.

Polishing gear.

Reading.

Sparring with quarterstaffs or clubs.

Running laps.

Practicing a marching tune.

Orcs.

Voice lines - idle.

"Warmer than usual, isn't it. Spring in the air."

"You've never even seen a grizzly. I'm not trusting you to track it."

"It's your wolf, sure, but that's my beef it stole, and I'll swear at it all I like."

"Anybody around here have a mirror?"

"Beautiful view. Beautiful. Wish I had some paint, maybe."

"Doesn't taste quite done. Let it simmer a bit. Otyugh's good, but unless you like your meat tough as wood, let it sit."

Voice lines - battle.

Enemy wounded mildly. "It bleeds!"

Enemy wounded severely. "Fail the fight, marauder! I have the upper hand!"

Enemy killed. "Another notch on the blade."

Ally wounded mildly. "You dare strike us?"

Ally wounded severely. "Orcish blood is not yours to spill like water, marauder!"

Ally killed. "Vengeance and destruction!"

Enemy caster on the field. "The enchanter's hands for the one who kills her!"

Enemy Barbarian rages. "A worthy fight! Face me, noble enemy!"

Enemy Rogue sneak attacks. "Treacherous coward! Scurry back to the shadows, roach."

Multiple attacks fail to hit enemy (heavy armor). "A stone to hew, my brothers. Fetch your picks!"

Multiple attacks fail to hit enemy (light armor). "A bird to snare, my brothers. Fetch your arrows!"

Warchief uses Battle Cry. "BLOOD! SKULLS! GLORY! DEATH!"

Idle animations.

Stirring a stew-pot.

Crafting a shield.

Gambling with knucklebone dice.

Playing a lazy tune.

Fetching water.

Reading Orcish poetry.

Drow

Voice lines - idle.

"If you bought a real bluefrill lizard for that price, I'm going to the Watch House and reporting a theft."

"I know, I know. But if all spiders are Lolth's children, she should keep them away from where they'll get stepped on."

"I don't think male objectification is that much of an issue, but that's just me."

"Yes, you told me about the time you saw the moon. You may recall the fact that I was there when you did."

"Driders. Ugh. I'd rather serve under a Duergar. At least you can tell their women and men apart."

"Phase spiders? Don't make me laugh. It's an urban legend. Came of Driders moving around so quietly, see?"

Voice lines - combat.

Ally wounded mildly. "You'll live! Back in the fray!"

Ally wounded severely. "Keep your guard up, you failure!"

Ally killed. "Good riddance. Weakling."

Enemy wounded mildly. "The first of many, intruder."

Enemy wounded severely. "Does it sting, lightbather? Do you wish you had never left your scorching lands?"

Enemy killed. "Blood unworthy to stain my blade."

Enemy Arcane caster (female) on the field. "An occupation ill suited to you, miss. Allow us to alleviate you of it. Fatally."

Enemy Arcane caster (male) on the field. "They've got a Sorcerer, beware!"

Enemy Divine caster on the field. "Heretic Priest, Lolth shall wrap you for damnation!"

Enemy Rogue sneak attacks. "You merely adopted the darkness. We were born in it, raised by it!"

Enemy gains the Poisoned condition. "Wither, lightbather, sicken and wither."

Idle animations.

Strolling.

Reading.

Practicing fencing.

Polishing gear.

Tending to riding lizards.

Practicing archery.

Kobolds.

Voice lines - idle.

"Hey, catch!"

"Go away, I'm nearly done working on this. Just gotta make sure the gears work right."

"Those dice are clearly loaded! Clearly! I can see it with my eyes closed! Gimme my gold back!"

"O Tiamat, Fivefold Queen, grant my brother Zol son of Cruzi repentance in Your eyes, and return him to health, among all Your subjects, in Your holy kingdom. May our prosperity be your will, and may we merit wings of glory, Amen."

"Three hundred teeth of Tiamat. What a lousy haul, huh, guys?"

"We're running a pick-up Skull-skull, anybody in?"

Voice lines - combat.

Ally wounded mildly. "Careful!"

Ally wounded severely. "Watch it! Get back or you'll buy it!"

Ally killed. "Aw, ____. I knew that guy."

Enemy wounded mildly. "Hah, take that!"

Enemy wounded severely. "For the Dragon Lord! Finish him off!"

Enemy killed. "Dibs on her boots!"

Enemy Dragonborn on the field. "Um..."

Enemy Draconic Origin Sorcerer on the field. "Guys? Do you...feel that?"

Enemy Arcane caster on the field. "Tiamat save us, what did he just do?!"

Enemy triggers trap. "Yes! So worth the four weeks I spent on that!"

Enemy destroys trap. "No! You can't do that! Go back! No!"

Multiple attacks fail to hit enemy (heavy armor). "Does he have scales?"

Multiple attacks fail to hit enemy (light armor). "Can she fly?"

Enemy Barbarian rages. "He's gonna breathe, look out!"

Idle animations.

Tinkering with tiny mechanisms.

Playing catch.

Playing Skull-Skull.

Polishing coins while whispering prayers to Tiamat.

Playing a complex board game.

Weaving a camouflage net.