Stone Cold Steve Austin just threatened to open a can of WHOOP-ASS all over Justin Bieber ... warning the pop star that if he doesn't straighten up, he's gonna catch a Size 13 in his ass.
The former WWE champ was on "The Arsenio Hall Show" last night when he issued the ultimatum -- shape up ... or else.
Stone Cold says he loves kids ... and just wants to make sure Justin gets on the right path before it's too late -- but he thinks an ass-kickin' is the only thing that'll get through to the Biebs.
"Sometimes you just got to keep it simple."
Stone Cold Steve Austin
I'm Gonna Kick Bieber's Ass
If He Doesn't Straighten Up
1/31/2014 12:00 PM PST BY TMZ STAFF
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