Adj. Derivation of Pacific Northwest American slang, early 21st century.
To have an ass which smells and looks like that of a hamster's.
By implication the person uses cheap toilet paper, is poor, and unwashed. The further implication is the person eats over processed food with little to no nutrition; therefore, their posterior is unshapely and the body can be likened to a pear, or hamster's figure.
"Have you seen the hamsterass on that trailer park bitch?"
"Jesus Christ! look at the hamsterass on the Wal-Mart greeter."