tuchus
noun
tuch·us ˈtu̇-kəs 
plural tuchuses
slang
: buttocks
These wise words recognize the truth about teens: They're a tremendous pain in the tuchus. 
The Lewiston (Idaho) Morning Tribune
The Lewiston (Idaho) Morning TribuneThe world already has competitions for talent and achievement, irrespective of how one's tuchus looks in a bikini. These competitions have names like "the Nobel Prizes" and "American Idol," and the standards are way higher. Gene Weingarten
Gene Weingarten
Word History
Etymology
borrowed from Yiddish toches, tuches, borrowed from Hebrew taḥath "under, below"
First Known Use
1886, in the meaning defined above