Gutter Mustard 

When someone is so drunk they walk out of the bar and puke in the gutter or on the curb. The vomit is normally a yellow hue from all the beer they have consumed; like mustard.

Oh look there goes Jim he is making Gutter Mustard again

Gutter Mustard by Hearevil October 1, 2010

The Hen's Mustard 

Used colloquially to mean an unnecessary addition of something 'Exciting' to what is already considered a functioning - if boring activity/object/product

"I used to quite like Dave's car, but that spoiler really is the Hen's Mustard"

The Hen's Mustard by navarrone906 March 14, 2017

Sharty Mustard Butt 

When somebody sharts in their underwear and wallows around in it for a long period of time. The color and texture resembles a mustard like substance.

Brian is a sharty mustard butt.

Sharty Mustard Butt by KrissyNJbo June 19, 2010

mustardish 

A) a condiment, that's, as the name implies, a combination of mustard and relish
B) a color that's a mixture of mustard yellow and relish green
C) adj: something that's dark, murky, and possibly yucky, combined

Ron,, from the Harry Potter series,: yuck, my mom sent me a mustardish sweater.

Harry: it's actually maroon, you can't properly see the colour, due to the lack of light.

mustardish by Uncle Dimma July 20, 2013

Mustard Gut 

Bad case of the shits.

Quick pull the car over at the next gas station. I got the mustard gut and about to shart my pants.

Mustard Gut by Eaton Holgoode June 8, 2016

Playing Mustard 

Involves working your ass off for a few days prior to taking time off work, as opposed to playing catch-up (ketchup) upon your return to the office afterwards.

"Hey Bryan, you wanna duck out early today and play a quick 18 with Frank and Toby down at the country club?"
"I wish man. I’ll be in the office playing mustard for the next 3 days before Krista and I head to Bermuda for our 10-year anniversary next week."

Playing Mustard by Cheeky Mirth February 4, 2016

Shoe Mustard 

When your dogglestyle cream pie drips onto your kicks.

I Left my Jordans on for more traction, now I got this big ass blob of Shoe Mustard that won't come out. I'm lucky it wasn't truffle butter.

Shoe Mustard by Jogney brogden October 29, 2018