Most singers just wanna rock and roll all night, but some end up finding happiness in their family lives ... and we want to see if you can guess who this proud grandpa is!

We caught up with this frontman back in 2023, just after his second grandchild was born ... and you already know he was super stoked about adding another kid to the family!

And sure, he took some time to put his John Hancock on some fans' merch ... but we think he just wanted to get back home and spend some time with the baby -- we're sure he's gotten real familiar with his grandkid since then!