Aside from poker players, the "is this a full deck of cards" question comes up from time to time.
Normally I just explain that I have cards signed and sometimes destroyed.
I just started doing a cannibal cards routine. It's a much better answer. "Hey, is this a full deck of cards?"
"Oh. You see... there are a few cards in here. They're kind of... sick. They eat their own kind."
I go into the cannibal cards but at the end, the cannibals vanish and the eaten come back.
"lol just kidding, people sign and keep cards all the time. Here, you should too!"