Also found in: Dictionary.
mess with (someone or something)
1. To change, fiddle, or play with something, often without permission to do so. My tools are not toys—please do not mess with them. Hey, don't mess with the thermostat—it needs to stay at 65 degrees.
2. To clash with someone or something. That group of boys is dangerous—don't mess with them.
3. To tease or mock someone. Sarah's a very sensitive kid, so don't mess with her.
4. To confuse or puzzle someone. One minute he's flirting with me, and the next, he's completely disinterested. His mixed signals are totally messing with my head!
mess with someone or somethingand monkey with someone or something
to bother or interfere with someone or something. Come on, don't monkey with my new camera. Don't mess with me unless you want trouble.
Interfere or associate with; also, annoy, bother. For example, Our group won't mess with those street musicians, or I told him not to mess with me or there would be trouble. [Colloquial; c. 1900]
1. To alter something improperly: Don't mess with the arrangement of the chairs—they're all set up for the meeting.
2. To deceive or confuse someone or something: The horrible accident really messed with my head.