A man of low standards in reguards to sexual partners. A true Shagnasty will quite happily have sex with someone he finds physically repulsive. A shagnasty never admits to sleeping with ugly girls and to most people may seem completly celabet.
> "you hear about john?"
> "what happened..?"
> "He got caught at the old peoples home trying to organise a geriactric orgy."
> "lol, that guy's a shagnasty"