Grimothy can be an adjective or a noun used to name something ugly, smelly, bedraggled and gross or something that disgusts the speaker

(noun) A successful type of theft which results in an acceptable, impressive and rewarding payday for the protagonist.

A tiny black kitten that eats butter and begs for bacon

Grimothy's are the biggest bitches you will ever meet. If you even make eye contact with one they shit themselves and let you fuck their girlfriend.