A shit smear on your asscrack or in your drawers that includes a non-shit chunk. Said chunk can consist of chile seeds, any tree nut, undigested items (including paper, metal and wood), Capt'n Crunch and more. This does not include klingons.
I hate doing laundry because dad always has chumpstains in his underpants.

Dude, I went to eat Erin's pussy and the bitch had a gnar chumpstain! She must wipe from back to front.
by archscientist March 2, 2010
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