When I’m doing close up magic, one thing that I don’t do is have people sign cards. There’s frequently a strange hesitancy when you ask people, like they aren’t sure exactly what you want them to do. Instead I have people draw a picture on the card.
I say, “Draw a picture on the card, it can be anything…Bigfoot fighting a ninja, so it’d just be a picture of a bigfoot. I won’t judge you…till later. I don’t care what you draw, I’m not your mom…wouldn’t be the first rocket ship I’ve seen today.” That has 2-3 laughs but it also gives them a moment to think about what to draw and I disarm them about worrying about the drawing being bad. It also takes away the incentive for a teenage boy (or drunk adult) to draw a penis as I’ve already gotten the laugh from that.
The other thing this does is gives me a real moment in the show that’s happening now that I can comment on. I can talk about the picture and everyone knows this is real and not preplanned.
Play around with using alternatives to signatures you might like it.