Johnny Manziel: U.S. Party Tour Continues ... To L.A.'s Hottest Club

Johnny Manziel won't stop until all 50 states feel his turn-up ... Miami earlier this week, Vegas this weekend ... and now L.A. ... having been seen out Thursday night at the hottest club in the city.

TMZ Sports has video of Manziel leaving The Nice Guy ... the hot spot du jour for young celebrities in Los Angeles ... where the likes of Justin Bieber, the Kardashians, and Leonardo DiCaprio have all partied recently.

Johnny's probably in town because he's scheduled to attend the big UFC 196 fight in Vegas Saturday ... and Sin City is just a hop, skip, and less than a hour private plane ride from L.A.

Same questions remain though ... with everything going on with Johnny right now -- including a grand jury looking at his ex-girlfriend's attack claims -- are his partying ways hurting his NFL future?