Yar!: Beat the Pirate Invasion.
Player: 1 Goblins: 0: Beat the Goblin Invasion.
One Lucky Terrarian: Obtain the Slime Staff.
Eye surgery gone wrong!: Beat the Eye of Cthulhu.
What's in that head? A brain? Not anymore!: Beat the Brain of Cthulhu.
He's just trying to help!: Beat the Wall of Flesh. (The ''He'' is the guide.)
You're a good boy by helping an old man!: Defeat Skeletron.
Worms aren't a big deal, I fish with them!: Defeat the Eater of Worlds.
Couln't help but killing a mother bee: Kill the Queen Bee.
I'm the king now!: Kill King Slime.
You think it was necessary?: Kill a bunny.
Robots are the future? Well this robot is hopefully not the future!: Kill The Destroyer.
Eyeballs EVERYWHERE!: Kill The Twins.
Not a skeleton, but a metalton!: Kill Skeletron Prime. (Metalton = Metal Skeleton)
They all wanna live in your house!: Obtain all NPC's.
Santa Claus is coming to (your) town!: Obtain Santa Claus.
You thought a flower could defeat me?: Defeat Plantera.
This is MY temple!: Kill Golem. (Indeed it's a reference to shrek)
So, first a flower now a fish? This is getting ridiculous!: Defeat Duke Fishron.
Player: 2 Kings: 0: Defeat the Pumpking.
ANOTHER TREE? Plant, Fish and Tree, what's next? Santa claus tank?: Defeat Everscream.
So I was right wasn't I?: Defeat Santa-NK1.
Player: 2 Queens: 0. No one can stop me now!: Defeat Ice Queen.
A tree? I have no words.: Defeat Mourning Wood (that sound weird)
A moon event? Well that's something you don't see everyday.: Defeat the Lunar Event. (Like go to wave 15 or however it works)
The sun is blocked and everything wants to kill me?: Get a solar eclipse.
So the moon is red, everybody mad.: Get a blood moon.
It's right from the heavens. And also VERY hot.: Gather Meteorite.
You can no fly infinitely, well not really.: Get wings.
Who needs doctors?: Get 1 crystal heart.
I've been searching for AGES. Still no doctors needed.: Get 400 life.
Fruit is heathy, it's all gold now.: Get 500 life. (This is ANOTHER reference to shrek, or shrek is love shrek is life.)
Who you gonna call?: Die in Hardcore and become a ghost.
I ain't afraid of no Ghost!: Kill Ghost (Halloween-only enemy)
These are the ones I could think of, I hope you think about them.