A modernized version of the old standby, "friend of Dorothy", meaning a (usually flamboyant) homosexual male. This is, of cours, in reference to Liza Minnelli, who inherited her mother Judy Garland's (aka, Dorothy from Wizard of Oz) primarily gay audience, and is equally worshipped and idolized by the gay community. However, with this modernized term comes a modernized definition, which now also includes lesbians. Minnelli's extensive charity work and advocacy for gays and bisexuals earns her this title.
"Of course he's going to Pride Week, he's a friend of Liza!"