You know, the stuff your character spurts out when you get boons, get profession-specific effects (switch attunements on Elementalist, use Photon Forge on Holosmith, etc.).
My favourite ones mostly come from Charr.
"ARMORED UP" (nothing special content-wise, but I just love the way a male charr says it)
"KILL SHOT" (love this one because it reminds me of early 2000s arena shooters)
"CAN'T KEEP A GOOD CHARR DOWN" (I know humans use this too but with Charr it sounds better for some reason)
And, let's not forget the try-hard champion,
"I COULD OUTRUN A CENTAUR!" (I love how on-the-nose fantasy bait this is).