Used seriously: A freak, one who was born defective.
Used jokingly: One who is very
strange, unattractive, uncouth, and/or trashy, which could possibly be ascribed to birth defects.
Taken from the novel "The Handmaid's Tale" by Margaret Atwood, where a shredder is one who is the defective product of
radiation altered reproductive cells.
All that makeup and bleached
hair can’t hide the fact that
Megan is a total shredder! That poor girl was born with a big
head and has no social skills!