[davidw]

Unoriginal or not funny ones; if they're unique and not some lame meme, they'll often get upvoted

[maxerickson]

The mods discourage humor because it tends to metastasize into tedious offtopic threads, which I guess is true enough.

Readers think they punish bad jokes and reward good ones, but the stupid Butts pun is doing great while the absurdist gem about Leonard Nimoy secretly wanting to be Kirk and living it out for a year in the white pages (and then someone working with him forgetting his name!) was nuked from orbit.

[xkcd-sucks]

The humor just has to be dry enough to maintain plausible deniability. Kind of like flirting in a corporate setting

[excalibur]

Or rubbing your eyes with sandpaper.

[jacobush]

It's the only way to be sure!