Is it wrong to lie and make false statements, even in lighthearted humor?

For instance, the kids and one youth leader in my youth group have this (slightly irritating) habit of saying something that's not true out of humor, and then when the joke's over they'll say, "No, I'm just kidding". Is that acceptable?

(Not to kill anyone's fun, but this thought occured to me when looking at the Outrageous Claims thread in Christian Fellowship. Though I fear posting this may make me a hypocrite, since I've participated in that thread.)