What is Usi?
1.
Unidentified Sex Injury
Those bruises, cuts, muscle strains, and torn ligaments that happen after a night of vigorous sex - and you cannot remember exactly what you did to cause it.
"Holy crap! My one leg is completely covered in bruises, but I don't remember what we were doing and how it got that way!"
"Dude, that is a serious USI."
See