I understand that this is off-topic, but is it really necessary to downvote it to invisibility? It's a silly joke. It costs you two seconds of your life to read it, and none for laughing if you don't find it funny. Just move on.
I think it's meant to be. Much as I love a bit of humour, take a look at reddit. Endless pun-threads and stupid jokes do drag down the quality of conversation - and people are no doubt afraid of the slippery slope.
As things stand, I like HN the way it is, and if I feel like something a bit more laid back then i read proggit.
A reasonable answer, but I keep thinking that there has to be some middle ground between pummeling the occasional (and clearly not mean-spirited or cruel or nasty) joke and the barbarian hordes of pick your least favorite other place.
Edit: Based on the voting, I'm clearly in the minority, so I'll leave it alone in the future.
Oh, you meant _programming_ books. Never mind!