i'd like to put together a running list of things i find funny that just never seem to get old. here's the first few that come to mind.
1. breaking in on a joke midway, hearing a ridiculous punchline and then having everyone break out in uproarious laughter.
e.g. "... so i said rectum?! damn near KILLED EM!" - "HA HA HAAAAAAAAAAA!"
typically, the comedy is based heavily on the delivery. being really loud and over-excited is key. you need to say the punchline as though your voice is going off a ramp ... "and then i said 'oh yeah!? my dog does the EXACT SAME THING!'" - "HA HA HA HOOOOOOO!" (i'm actually making myself smirk a little bit as i write that last one off the top of my head. see? it really is always funny to me.)
2. [some thing or activity] makes [something that is typically ridiculed] look like [something that is typically revered].
e.g. "white chicks" makes "corky romano" look like "citizen kane".
coming up with blank1's and blank2's (makes [blank1] look like [blank2]) that are really really far apart is helpful.
more to come, i'm sure. please comment on your own and we'll see if they make my cut.