Lil Kim -- Pisses Off Gay VIPs

Lil Kim is in danger of losing a huge portion of her fanbase ... after stiffing a large group of gay fans who paid big money to meet her over the weekend.

All the rapper had to do to score a fat $23,000 payday Saturday was mingle with 100 high-paying fans, then do a quick show to help celebrate the club's 5th anniversary.

Not a bad gig, right?

But The Manor claims she showed up late and skipped out on the scheduled meet and greet ... and now they're on the hook for refunds they had to shell out to the VIP fans.

Kim, who's fattened her wallet in recent years by almost exclusively playing gay clubs ... claims it's the promoter's fault because she was never told about the meet-and-greet. See flyer below.

The Manor's attorney Howard King tells us they plan to sue Kim ... but he says she already got her comeuppance ... because concertgoers booed her when she left the club.