sit-upon

[ sit-uh-pon, -pawn ]
/ ˈsɪt əˌpɒn, -ˌpɔn /

noun

a piece of waterproof fabric or other material carried by campers, hikers, etc., and used for sitting on wet surfaces.
Chiefly British Informal. the buttocks.

Origin of sit-upon

First recorded in 1835–45; noun use of verb phrase sit upon
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019