Justin Bieber Party -- Naked Girls Everywhere

Justin Bieber's Gatsby party on Friday was FILLED with naked chicks ... as far as the eye could see ... this according to sources inside the party -- and all Justin's celebrity friends were there, including Floyd Mayweather and Chris Brown.

Sources at the party tell us, there were at least 20 "big booty" strippers there -- and the girls who weren't strippers felt self-conscious wearing clothes, so they stripped down too. Basically, every man's dream.

And Bieber was tipping like a pro -- we're told he had stacks of ones and made it rain all night, dumping more than $10,000 in cash on the girls. One dancer tells us she made $1,300 alone.

According to sources, Breezy, Floyd, T.I., Trey Songz, and Snoop were there too. We're told Snoop had his priorities straight though, spending most of his time playing strip beer pong with some ladies.

As for booze and weed ... we're told there were 3 open bars and plenty of kush to go around.

TMZ broke the story ... Bieber's party was a rager and Bieber's neighbors weren't happy -- one even filed a police report, claiming Bieber was disturbing the peace.