Acronym for Super Itchy Bunghole Syndrome, usually brought on by wearing the wrong underwear on a really hot day while moving furniture up three flights of steps with a raging case of diarrhea.
Best cured by using a medicated powder.
Related to Swamp Ass
, but you're inclined to scratch.
Honey, will you please powder my bunghole for me? I've got a nasty case of SIBS.