Logic would dictate that if you aren't laughing while playing a game, than you aren't enjoying it. If you aren't enjoying it, than you have no business playing it.
You don't have to laugh at something just because it's funny. It could be out of pure, unadultrated joy of the slaughter. When you finally kill that ************ in God of War that mutilated you twenty times, you laugh. That's joy, and that's the point of the game, I think.
Mmm...by way of an example, a couple jokes between me and a friend revolve around things that aren't nessecarally funny (out of context). For example, the last battle in Fire Emblem; Path of Radiance involves your dragon character calling for help. If you have Nasir (the harder one to get, requiring you defeat The Black Knight) he says, "Ike, I don't like these odds!" Zeb happened to have only Ike and Nasir; he figured Ike was strong enough to beat the crap out of anyone who stood in his way. Which he did.
Apologies 'n stuff