When you are playing baseball and you're up to bat, you bunt the ball so amazingly that it hits the pitcher and as a result; you jizz in your pants.
"Dude, did you see Justin's buntkum at the game yesterday!?"

"Naw man i missed it"

"It was great! You could see the stain in his pants."
by Dr. Knockers and bear October 5, 2016
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