I guess it still might be someone's fetish. Some kind of blumpkin afficionado, or whatever.
I always figured the idea for the whole blumpkin concept must have been proposed by the blower, rather than the blowee. NOBODY has the balls to SUGGEST that shit. Like, "hey babe, I've got a wild idea...I'm about to go take a shit. You wanna suck me off while I'm doing it?"
If you're willing to say that, you've got problems even taking a shit, because you can't sit on a toilet with balls the size of watermelons.