Definition of rotten egg:
(n) :
(slang, idiomatic, humorous, childish) A person who is the latest, the last, or the slowest in a group to arrive somewhere or to perform a certain task.
(n) :
(chiefly transgender slang) An egg (“closeted transgender person”) who overcompensates by being actively transphobic.
(n) :
Used other than figuratively or idiomatically: see rotten, egg.