Cleveland Cavs Fly to Vegas to Party ... Champagne Nightclub Celebration

The Cavaliersmade a pit stop on their way back to Cleveland -- landing the team jet in VEGAS for a wild Sin City championship celebration ... complete with insane champagne showers!

LeBron, J.R. Smith, Kyrie Irving and the rest of the squad rolled into XS nightclub at the Wynn -- and were greeted like they just won the Larry O'Brien trophy ... 'cause they did!

J.R. Smith even took his shirt off at one point ... because ... well, why the hell not?

Congrats!