back door bagpipe

Inserting a straw into a person's asshole, taking a hit off a joint, and exhaling into rectum. Then remove straw and press firmly on stomach forcing a smoke fart out. It is then inhaled again and the process is repeated.

My ass is still smoking from that back door bagpipe last night.

Man this is some good weed. Anyone up for a back door bagpipe?

Billy brought in a bag of weed begging for a back door bagpipe.