To bend blow is too give one head (suck a cock) whilst getting fucked up the arse (being bummed). The position needed to perform this is to bend over and to suck a cock is to give a blowjob. Hence Bend Blower.
"We made Stephaine a BEND BLOWER yesterday mom. Yes she sucked my cock and then Roger bummed her up the arse."
"What a BEND BLOWER!"