The phrase "bad rap" is an idiomatic expression that means to receive a negative or unfair reputation, often due to misinformation or misunderstanding. It can also refer to being blamed for something one did not do or being treated unjustly in some way. The term comes from the world of hip hop music, where "rap" refers to a rhythmic spoken word poem and "bad rap" means receiving negative attention or criticism that is undeserved.