I'm still relatively new to magic, but when I make a joke, I like to have a sort of self awareness about magic, as though to say "It's really magic you guys *wink*". One line that I really like to use is one I first heard from Justin Miller's video on Ellusionist "Army of 52"*. After turning a card face up so Justin can see it too, the spectator makes a comment in surprise, and Justin replies "It's okay, I've seen this trick before". Something I've always wanted to do, but never full developed, was to start taking as though the trick is to be taken seriously, kinda like the infamous Chris Angel tends to do, but slowly make the story surrounding the trick more and more ridiculous, before kind of flubbing a line, pausing for a second, then performing the trick in silence.
*
http://www.ellusionist.com/army-of-52.html