The act of putting a balloon, water balloon size preferably, in another persons anus and then blowing it up with mouth or straw until it pops, causing extensive amounts of pleasure.
"What happened to jimmy?"
"I don't know, ever since that blowbob at that party he received, he hasn't been the same."
The act of providing oral pleasure to a man's cock while sticking your finger in his juicy ass
James blowbuttaged a handsome chap in the men's room at Bloomingdales...his turgid cock felt good in Jame's mouth and his tight ass squeezing down on Jame's finger made Jame's shot his wad all over the stall floor.