Posted on Mon Feb 13th, 2012 1:15pm PDT
Justin Bieber, who is just weeks away from turning 18, is showing off his developing pecs while horsing around at the beach in Malibu with stepbrother Jaxon.
The "Baby" singer, sporting a beanie and his numerous tattoos, enjoyed swinging the little tot around in the sand while his dad, Jeremy, looked on. Be careful, Biebs ... you don't want to pull your little bro's arms out of the socket!
Nothing like bonding on the beach in the 'bu!
See more of Justin shirtless in our gallery below.
SEE THE GALLERY Justin Bieber Goes Shirtless In Malibu
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