I think that Perl programmers are brighter than average and likely more widely educated, either academically or experientially. They have many interests, a good sense of humour, and probably know a variety of languages (both spoken and programming).

So linguistics is a natural for this group: dissecting language, both spoken and programmed is just 'fun' for this group. Something an Apocalypse or an Orwant rant (the one at YAPC 19100 was the one I remember) is good clean fun and terrific entertainment. Or Ingy's talk about Inline::C at YAPC 2001. Or any talk by Damian Conway.

And that's one of the reasons I love to visit PM, or go to YAPC; there are so many bright folks around, there's rarely a dull moment.