fool about withidiom
Definition of fool about with
1 : to use or do (something) in a way that is not very serious I'm not really a painter; I just like to fool about with paints.
2 : to handle or play with (something) in a careless or foolish way Don't fool about with that gun.
3 : to have sex with (someone who is not one's husband, wife, or regular partner) His wife discovered that he was fooling about with his secretary.