Simp isn't an acronym (I don't think, or at least not generally used as one), it's just slang. It's not derived from simpering though, it doesn't mean anything

Simp isn't an acronym (I don't think, or at least not generally used as one), it's just slang. It's not derived from simpering though, it doesn't mean anything like that. It refers to sad men who are led around by their nose by women who have no interest in them. Those men are simps (also known as white knights, suckers, marks etc).