Illicit or embarrassing activities such as urinating, smoking marijuana, or giving (not receiving) oral sex. Named after the idea that one might prefer to do these activities behind a shed.
This is a common colloquialism in south-eastern Wisconsin.
Man that party was fun, but it got hilarious when we caught him doing that shed-shit.
An old saying, expressing great annoyance. Originates from the early 1800s, first used when individuals desperate for the toilet found the only lavatory to be engaged.