Luke Bryan Thanks Extra Meaty Butt for Breaking Fall Onstage

Luke Bryan's counting his blessings for the extra padding that saved him when he took a nasty tumble onstage during his latest concert stop.

We caught up with the country star at Cecconi's Monday in L.A. ... and he joked his weekend slip-and-fall wasn't as painful as it looked 'cause he's got "a whole lot of meat back there" -- referring to his butt, of course -- which softened the landing.

ICYMI, the initial buzz was Luke went horizontal Saturday -- during his performance at the Coast City Country Festival in Vancouver -- due to a fan's phone that was left on the stage.

But, a later video angle showed he simply slipped on the floor ... perhaps on some moisture or liquid. Either way, Luke's told us he's still scratching his head over what exactly sent him plummeting.

He clearly didn't mind being the butt of the joke, though, as he spoke to us -- and also by the way he reacted with good humor seconds after going down.