YG DENIED at the Club ... Too Many Dudes, Bro!

And now ... YG gets a lesson in Hollywood nightclub politics, and that lesson is: A bunch of penises will get you nowhere, son!

The rapper showed up at 1 OAK on the Sunset Strip Thursday night with a whole crew of dudes, and we got this video of their repeated efforts to get in the club.

They tried the back door, then the front door. YG even got a VIP host on his side, trying to get him in the club ... but still got dissed by the mountainous bouncer who declared, "There's too many dudes."

Mind you, Justin Bieber and Wiz Khalifa had no problems getting into 1 OAK the same night, but as the bouncer put it -- "Wiz comes with girls!"

The more you know.