Urine that is left to settle in a toilet bowl. Comes from the energy saving saying that goes "if its yellow, let it mellow. if its brown, flush it down."

Not to be confused with Mellow Yellow which was a song by Donovan in the 60's composed when he took the drug Mellow Yellow. Also not to be confused with the drink popularized by Coca Cola.
"Stop leaving yellow mellow in the toilet! The dog drank out of it and licked my face!"
by Isar December 07, 2005
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1. that yellow mellow bitch was completely trippin out.
by Cameleo September 26, 2006
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this is ANY action taken for one to release obscure things such as tension, stress, everyday odsticales that can bring a one down.
"dude, you need to let your yellow mellow"
by flower420 March 06, 2012
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1. A song by the 60's song artist Donovan. The song's influence was from a short-lived rumor that a euphoric high could be reached by smoking banana leaves. The song became very popular in the late nineties after a cover was made for a series of Gap clothing commercials.

2. A Coca-Cola product with high caffeine and citrus flavor; not related to banana leaves at all.
1. (lyrics)- "...electrical banana, it's gonna be a sudden craze..."

1. (ex.)- "Did you see that Gap commercial? Who sings that 'mellow yellow' song?"

2. (ex)- "Wow, have you tried this mellow yellow stuff? It's like Surge, but new!"
by Coqui August 12, 2005
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1) A song
2) A drink similar to Mountain Dew
3) Tussionex - Prescription cough syrup that contains 10 mg of hydrocodone per 5 ml of liquid. Way stronger than promethazine w codeine syrup, but does not taste as good.
1) Let me hear that song Mellow Yellow.
2) Lets get some Mellow Yellow and mix it up w some of that presription mellow yellow...tussionex.
3) I'm throwed off that Mellow Yellow bro. Shit hits me way harder than that purple.
by Mike Roper July 23, 2008
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Code word for the painkiller NORCO® (hydrocodone bitartrate and acetaminophen)
I popped 3 Mellow yellows and I just feel like chillen.
by Bigmush818 February 21, 2011
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