play about

1 : to have sex with someone who is not one's husband, wife, or regular partner He's not the kind of guy who plays about. —often + on She's been playing about on her husband. —often + with She's been playing about with one of her coworkers.

2 : to deal with or treat something in a careless way When it comes to protecting his family, he doesn't play about. —often + with You can't play about with diabetes; it's a very serious disease.

3 : to use or do something in a way that is not very serious It's time to stop playing about and get busy. —often + on I spent the evening playing about on the piano/computer/Internet. —often + with I'm not really a painter; I just like to play about with paints.