I think one of the biggest things is to be conscience of what kind of humor you're aiming for.
Physical humor seems to work REALLY well in multiplayer games. Anyone who has played Halo has had a those unscripted slapstick moments where you're doing a little victory dance and a flaming car flies out of the sky and squishes you, or those moments in Little Big Planet where your friend is jumping over a spike pit at the same time as you, but you're not going to make the jump, so you latch on to their little burlap ass in desperation and you both fly, screaming, into the abyss.
Physical comedy works the best in those "I can't believe that just happened" moments, like riding an ATV tandem in Saints Row 2 when an explosion launches you five hundred feet in the air and you and your friend are both screaming and clutching on for dear life and it lands perfectly and zooms off into the horizon, or pretty much anything that happens in Mario Kart.
Actually, having a co-operative game in which you can still screw your teammates over is pretty much always funny. Battle Block Theater is unbelievably hilarious, and 90% of the humor just comes from shoving your teammate off a cliff.
Now actual wit is another thing entirely...
Physical humor seems to work REALLY well in multiplayer games. Anyone who has played Halo has had a those unscripted slapstick moments where you're doing a little victory dance and a flaming car flies out of the sky and squishes you, or those moments in Little Big Planet where your friend is jumping over a spike pit at the same time as you, but you're not going to make the jump, so you latch on to their little burlap ass in desperation and you both fly, screaming, into the abyss.
Physical comedy works the best in those "I can't believe that just happened" moments, like riding an ATV tandem in Saints Row 2 when an explosion launches you five hundred feet in the air and you and your friend are both screaming and clutching on for dear life and it lands perfectly and zooms off into the horizon, or pretty much anything that happens in Mario Kart.
Actually, having a co-operative game in which you can still screw your teammates over is pretty much always funny. Battle Block Theater is unbelievably hilarious, and 90% of the humor just comes from shoving your teammate off a cliff.
Now actual wit is another thing entirely...