Someone who is acting suspiciously and/or is doing something naughty.
Jessica is up to no good, she is messaging more than one guy again!
by Leeboylondon April 25, 2015
Used by fast talking southern folk. It basically means "How are you?"
Southerner: Wha chu up to no good there brotherman?

Yankee: What the fuck did you just say?
by damnstraight November 6, 2004
In the traditional sense, if someone is "up to no good", they're doing something bad, or wrong.

WE ARE NOT TRADITIONAL.

We are a collective that defies all odds, a group of individuals, comrades from all walks of life.

Regardless of whether we have different beliefs, careers, experiences or values, we are all Up Two Know Good.

"Up Two" as in two steps ahead, in the lead, striving to win.

"Know Good" as in seeking Knowledge of Self, living the "good life".

We have chosen to commit to knowing better, with intentions of doing better.

We are seeking out the very best in ourselves and in every aspect of our lives.

(Taken from UpTwoKnowGood.com)
What's Good?

Those kids are Up Two Know Good.
by What's Good October 15, 2014
I'll tear you out of that red sweater and khakis and screw your brains out.
Jake: "No. Really. There are no markdowns, just great rates"
Maya: "Pull around back in twenty minutes. I'll hook you up with the good parts."
Jake: "When you want the real deal....."
by feed the dogs January 4, 2021
The opposite of Down Bad, where someone who is Up Good can either be a) not depressingly horny, b) depressingly wholesome, or c) very much anti horny.
Paul: Damn, look at her. Her ass is fat.
Tom: Dude, you’re down bad.
Sam: Tom, you’re so up good.
by JoseTheSpaceCrab December 2, 2020
Phrase that allows a person to see what is on the Marauder's Map. Told to Harry Potter by Fred and George Weasley
"When you want to open the map, say I solemnly swear I am up to no good; to close it, say mischief managed.
by LitTeacher June 27, 2015
Bro 1: Yo, I’m feeling good today!
Bro 2: Bro, you’re up good.
by Cul Gi January 19, 2021