Gash heavy is a crude term used to describe the patrons of a bar. If the bar has a lot of males in it, the term sausage party might be used. When a bar or club has a lot of females of legal age the term gash heavy would be used.
Big bob: dude get here quick ! , this place is gash heavy !
scott: how was the club last night Bob ?
Big Bob: Gash heavy man !
I guess i picked a bad time for reconstructive mangina surgery ! !