When you are caught off guard by someone who has the intention or is in the process of invading your cornchute with no prior concent or chance of warning.
Sucker punched in the turdcutter with a penis.

Jamie bent over in the shower and received surprise butt sex from Mike
by sexerscise instructor February 13, 2014
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Very hott anal intercourse brought on by an erect penis or three and a surprised anus that will soon feel the smooth stabbing feeling of the penis(es) ripping open their tight anus hole. brought on without consent. often causes internal bleeding and projectile diarrhea.
Those three guys from work were in the stockroom after hours at work when I bent over only to find 3 penises ripping apart my anus hole.

"SURPRISE BUTT SEX"
by the anus man July 11, 2008
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When a person puts a peanut filled balloon in their anal cavity and squeezes the peanut butter out in a projectile fashion into another person face.
do you know that girl Cindy? i heard she gives the best peanut butter butt boom surprises. i just want to get a really creamy peanut butter butt boom surprise.
by the dirty joay stain October 18, 2008
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