to be a killjoy. to ruin someone's happiness, whether they are drunk, or just really happy, with sad news or drama.
mellow, in a good mood, then someone tells you something saddening. u harshed the mellow.

"dude. your house is on fire."
"damn. you totally harsh my mellow."
by kiley hamre November 7, 2007
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1. To annoy someone and bring them down whilst they're in a good mood
2. To annoy someone and bring them down whilst they're high
1: "This guy's annoying the fuck outta me, he's totally harsh my mellow!"
2: "Like duuude, this guy just came along and was screaming at me and dude, whoa dude HE TOTALLY HARSH MY MELLOW man!"
by LordEuronymous May 27, 2012
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Bringing down my good mood.
I didn't like her.. she was really harshing my mellow, man.
by Julia May 7, 2005
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when you're peacefully blazed and something happens to ruin your high..
"Dude got baked and was screaming and shit. He completely harshed my mellow man."
by PsychoDice January 14, 2004
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When someone takes away from your high, or tries to be cool by fucking with you when you are buzzed. What happens when a nancy (see Nancy) brings down your elated feelings while high.
Dude, you're really harshin' my mellow.
by Duke March 13, 2005
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