The use of mustard or mustard bottles to  masturbate. Practiced mostly by men but can be practiced by women.
Anne: "Yuck, your dick tastes like mustard!"

Fred: "Sorry, I've been mustardbating"
by P+V=S March 24, 2010
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When you're fishing and you use mustard as bait to catch the fish.
"yesterday on free fishing day, I decided to mustardbate instead of master baiting (using worms)."
by Pacman's Little Bitch June 21, 2018
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