Quagmire: "oooh rriiiiiiight"

Stewie: victory is mine"

Stewie: "no sprinkles, for every sprinkle i find, i shall KILL you."

Peter: "Ok, here's another riddle. A woman has two children. A homicidal murderer tells her she can only keep one. Which one does she let him kill?"
Brian: "That's... that's not a riddle. That's ... that's just terrible."
Peter: "Wrong, the ugly one! "

and the best-
Stewie: "What the hell is this?"
Lois: "Sweetie, that's tuna salad."
Stewie: "Oh, is that what it is? Really? Because I could have sworn it was mayonnaise and cat food."