If Kellan Lutz ever invites you to hang out ... beware, because he pulled off an insane workout OFF A CLIFF IN AUSTRALIA!!
The "Twilight" star is down in Sydney and managed to "fit in a quick workout" while exploring an area called Barrenjoey Head ... high above Palm Beach.
Push-ups on the cliff, pull-ups under the cliff, and just plain posing -- all without those wimpy safety harnesses they used on "Bullseye" ... the adrenaline junkie reality competition he hosted.
It's all about the hang, bro.