[hummerabia]

Happened twice on my '06 while out in the desert both when crossing a dune ridge at an angle. I guess it's too much of a change in lateral angle for the airbag sensor and it thinks you are going to roll.
Also happened on a mates '07 when he slid down the slipface of a dune kind of sideways they popped when he hit the bottom. We advise all the local Hummer club guys to remove the airbag fuses before hitting the dunes.
It seems to be quite a common event over here in the desert, the dealerships have been forking out on a lot of side airbags under warranty.
A right pain in the a$$ when it happens as you are usually miles away from the highway and have to endure ringing ears and a tensioned seatbelt for the rest of the trip.
Scared the sh1t out of me the first time, second time i was kind of expecting it to happen even though the dealer said they had changed the roll over sensor to a revised one more tolerant of angle change.