If you get the chance to watch the Amazing Johnathan, he has a lot of good lines. One that I find particularly funny is he has a spectator pick a card. The spectator is told not to show the magician, but to show it to everyone else. The magician then takes that card, turns it over (so the face is facing him) and points to the back saying that there are no marks on the back in which he could use to tell what the card is.
One that I've seen Gazzo use in one of his live shows was "Okay, hold your card up and show it to the audience. Hold it up high! Now show them the back (as he pretends to peek)".
I sometimes keep a little plastic pile of dog poop in my pocket in case someone picks a jack, I take the card from them (palming the dog poop and placing the card on top of it, not letting them see it). I shake the jack and poop falls out from under the card and I say "...Ha, your jack [edited]". It's not insulting, but it sounds like one.
Another one of my favorite card jokes is to show a spread of the 4 queens and ask "Which one of these queens cant have kids?". No matter what theyre response, I hold up the queen of spades and say "This one, you know why? Because she is Spade (spayed, neutered, fixed...its a veterinary term)". It never fails to get a laugh.
Just my thoughts...