Josie Canseco Boozy and Butt-Flashing at Drake Party

Josie Canseco was TURNED UP on Wednesday ... with the model showing off her butt and talking about getting hammered on the way into a nightclub ... and it's all on video.

Jose's daughter (who's dating rap star Mike Stud) was with some friends outside of Delilah in West Hollywood where Drake was hanging out and they planned on joining the fun.

One problem ... the side door was locked.

Don't worry, the boozy bunch eventually figured out a Plan B and got into the party -- after telling TMZ Sports their NYE resolution is to get "f*cked up!"

Hey, she's 21. Like you were any better?