I was in the shower the other night and I came up with this great pun about Gengis Kahn. I don't remember it exactly, but I do remember that it had something to do with Gengis Kahn mailing out fraudulent coupons that promised great deals on helmets if someone would open the gates on the Great Wall of China. Then, as the mongol hords were running amok in China, the guy who opened the gates said to himself, "I've been Gengis Conned!"
Not really a pun I guess. Some would say that it isn't really even that funny. Those people have been Gengis Conned.