Jim Carrey Rebounding with Hot NEW Piece of Ass

9/17/2012 6:17 AM PDT

Jim Carrey -- Rebounding with HOT NEW Piece of Ass

Call him Ass Ventura.

Jim Carrey hit the beach in Malibu this weekend with a brand new thongtastic bikini chick ... just a short time after reportedly breaking things off with his last GF -- 23-year-old Anastasia Vitkina.

50-year-old Carrey is a LEGEND on the Hollywood dating scene ... cycling through stunners like Jenny McCarthy, January Jones, Renee Zellweger and Lauren Holly.

So far, the identity of the new chick with the great butt is unclear ... but we're hoping this one sticks around a while.