A mug is a person who is friends with your girlfriend who always cock blocks. she either is always talking to her when you want to or always tries to get invited to things with ur girlfriend.
Ben: June is being such a mug rn.
Dan: I know why does she want to go to the mall with us so bad.
Ben: Like does she know itâs supposed to be a double date.
Dan: IDK but I HOPE JUNE GETS HIT BY A CAR.