Fuck with

PHRASAL VERB{SLANG/PROFANE}
1. (FUCK WITH {object: someone}) tease jokingly in varying degrees of severity.

2. (FUCK WITH {object: someone}) intentionally provoke or threaten.

3. (FUCK WITH {object: something}) meddle with, adjust, or otherwise manipulate something. Usually expressed in a prohibitory or cautionary manner.
4. (FUCK WITH {object: something}) engage in an activity of the kind usually or typically considered broadly to be either illicit or immoral (such as drugs or criminal enterprise).

**See Also Non-Profane Equivalent: Mess with {SLANG/NON-PROFANE}

"Mess with" is entirely interchangable with "fuck with" in all ways, but is inoffensive entirely.

1. Don't be mad, Bob, I wasn't serious when I insulted your mother; I just like to fuck with people.
2. I suggest not fucking with him, he's been known to carry a gun and has a short temper.
3. For the last time, I told you never to fuck with the thermostat.
4. If you fuck with heroin, you're probably going to die with a needle in your arm.