Well, it's sacreligious, plus hints at cannibalism. But mostly, it's shock value that makes it funny.
OK, Rekrab, agreed, but tell me this: is shock value the most important aspect of Buk's writing, in the long run?
Sure, Buk has plenty of shocking, outragious hilarious lines. He doesn't shy away from them. But standing alone they're just cheap thrills compared to his ability to see and sense all the different aspects of life.
Shock value was a good thing to use when he was trying break into the field, to make it as a writer in the 60s. It makes good PR and gets you noticed, but
Absence of the Hero is closer to the essence of his writing. I'm with Roni on that.
Then again, I understand your instincts, there's something bookish about the title as well. "Absence" is not vernacular, it has a dry ring to it. Reminds me of the episode in Hollywood when Chinaski replaces the word "masturbate" with "jack off" in the script of Barfly. Jack off has more "bbq sauce".
On the other hand, again,
Absence of the Hero is actually a variant of "Don't try". Isn't it?
Works for me.