From Longman Dictionary of Contemporary Englishmess around with somebody/something (also mess about with somebody/something British English) phrasal verb informal1 SYSEX/HAVE SEX WITHto have a sexual relationship with someone that you should not have a sexual relationship with She’d been messing around with another man.2 INTERESTEDto spend time playing with something, repairing it etc Dave likes messing around with old cars.3 to use something and make annoying changes to it Who’s been messing around with my camera? → mess→ See Verb table
Examples from the Corpus
mess around with • A monster like that is nothing to mess around with.• Now he is messing around with education, and look at the mess that that will be in.• Above all, why were these chaps messing around with helium-filled contraptions, in an age of routine rocketry?• There we were, messing around with his things, and all the time he was dead as a doornail in Paris.• Years ago Pauline blew off his fingers messing around with homemade rockets.• We knew they had to go so we messed around with it.• We had some spare time, so we started messing around with samples and sequencers and stuff. 