mustard shart

The liquid that shoots out of a mustard container when you're expecting mustard, and not mustard juice/liquid.

This ruins a sandwich, even though you may have taken the percaution of squeezing it over the sink before your sandwich.

"damn, I made an awesome sandwich, but then I topped it off with mustard, and I got a nasty mustard shart instead!!"

mustard shart

When Tony eats an entire tub of mustard and subsequently shits his pants.

That Katz Deli Mustard Matt gave us was so good until I saw Tony mustard shart in his seat next to me.