Some witty comebacks that are appropriate for various occasions include sayings such as "I’m sorry but I didn’t order a glass of your opinion" or "I refuse to engage in a battle of wits with an unarmed person." IShouldHaveSaid.net lists a few other options as well, such as "If I give you a nice big straw will you go suck the fun out of someone else’s day?" and "Where’s your off button?"
A few more witty comebacks suggested by LaffGaff include "I’d give you a nasty look but you’ve already got one" and "If laughter is the best medicine, your face must be curing the world." Some comebacks may only be appropriate depending on the situation. Take for instance the exchange between a parent and child seen here: "Mom, stop, you never make jokes." A witty comeback from the mother might be "I made you."
When faced with an unsolicited opinion, a possible witty comeback is "Remember when I asked for your opinion? Me neither!" Then there is the popular phrase "Your Mom," which is commonly injected as a comeback in a variety of situations. Also, one other comeback for a chatty person might be, "Save your breath! You’ll need it to blow up your date."