The Gladiator star treated nine friends to a meal of mussels and chicken in the Carew Inn, near Tenby, costing £240 and then stunned the waiters by paying a generous sum on top.
His outing came during a break from filming Robin Hood at local beauty spot Freshwater Beach - a project he describes as an "interesting gig" because he's got naked and danced by firelight with Cate Blanchett.
But his generosity wasn't just financial. The Aussie actor - who has a band which has been known by various names, including The Ordinary Fear Of God and 30 Odd Foot Of Grunts - laid on an impromptu concert for the locals.
He led his band of merry men through a set that included Everly Brothers' hits, Bryan Adams' Summer of '69 and Sixties song Leaving On A Jet Plane.
"He could have paid and just left but they stayed instead and entertained us. Then he paid us that tip – it’s the last thing you expect," said one staff member.
"“He seemed quite friendly and chatty like a really nice guy, and he had a great singing voice.”