Mel Gibson and Stallone We Still Rock Out Even Though We're Old

2/15/2014 8:05 AM PST

Old guys can still rock out with the best of 'em ... something Mel Gibson and Sylvester Stallone proved Friday night in Los Angeles at a Kiss performance.

Mel and Sly attended a benefit event for a charity Gibson works with called Mending Kids International ... both actors were limited in movement -- but it's clear they're very into the performance.

If you look closely ... Dog the Bounty is also jamming out in the background.

Rock and roll all night.