Actually, the “blown up” method wasn’t quite as satisfying as anything from Caddyshack.
I used a first-generation version of these:
It pumps a mixture of propane and oxygen down the burrows and then ignites it. I quit using it after a couple of close calls caused by large wads of flaming cheatgrass being ejected from holes 25 yards away...
Wish I could rent one of those! Trouble is the groundhogs dig their burrows under my shed and my deck. Then what?