MAD MEL ‘ROID RAGE — HOPPED UP ON HGH?!

Superstar MEL GIBSON is sud­denly looking like a muscle-bound bodybuilder – and medical experts believe he has resorted to steroids, hu­man growth hormone or both to bulk up quickly for his role in Sylvester Stal­lone’s “The Expendables 3.”

The hunk-turned-hulk was recently pap snapped at the Beverly Hills Rejuvenation Center, which specializes in controversial, prescription-only hormone replacement injections.