I didn't shoot this photo with the intent of being humorous, but a lot of people have laughed when they see it. So be it!
I shot it during a dance photography workshop with Lois Greenfield in the year 2000, using a Contax G2 and 90mm Sonnar lens. All I was trying to do was contrast the musclebound strength of the guy with the extreme delicacy of the girl. I suppose it's this contrast plus the guy's somewhat nervous expression that amuse people.
I'm a big fan of humor in photography, but it seems to be quite difficult to do, as there isn't a lot of it that's really naturalistic to the medium. For me, the most consistent practitioner of it is Elliot Erwitt, and in his case what makes it work is that the humor isn't overt. Rather, his images contain contrasts that are so peculiar, yet so ordinary and natural, that the mind's reaction is delighted amusement at the dilemma they create.
I'm not saying my picture is in the same league, but I'd like to think the same mechanism is at work.