"A warrior kills, just like a murderer, but the murderer enjoys it." - Unknown.
"Just because I love a girl, it doesn't give her right to enter my room." - Sheldon Cooper, wise even when in love.
"This can end in one of two ways: Either you give up, or we kick you around until you give up. So, what's it going to be, the easy way, or the fun way?" - Sailor Jupiter (fic.)
"I'm sick and tired of being sick and tired." - Nick, Left 4 Dead 2, when really low in health.
And even tho quoting oneself is bad, here's one from a story of mine, from a combat training session involving one Usagi Tsukino...
Hakko: The trick to winning a battle is to be aware of your surroundings, and to use them to your advantage. Now tell me, Tsukino, what do you see?
Usagi: I won't tell you.
Hakko: Why?
Usagi: Because then you could use what I know against me.
Hakko: Good, you passed that test.
And to wrap this up, some ClapTrap awesomeness:
MinionTrap: Knock knock
FragTrap: Who's there?
MinionTrap: Wub.
FragTrap: Wub who?
MinionTrap: Wub wubwubwubwubwubwubwub-
FraTrap: ...You're dead to me.