Strapkeepers? it's hard to tell because all you can see is an inch or so of black cord at the endpin. But man, they work. I've got them on all my acoustics. I think of them as a ten dollar insurance policy.
Don't ever do that, by the way. Not because the Strapkeeper might let go - nothing short of a sawz-all could do that - but because endpins aren't designed to withstand that kind of torment, especially if they're not screwed down. (Hey pa! Cletus is dangling yore ol' D-45 out the window aga... never mind!)
I was fortunate enough to watch Ed Dopera build metal-bodied Dobros. I own one. You could hang a chariot from one of those things. Just don't actually drop it, or every guitar repairman you approach is going to shrug and refer you to an auto-body experience in a bad part of town.
Besides, if you really want to impress people, play upright bass behind your back. Slap style. (Now I have a weird bass player Kama Sutra thing going on in my head. I didn't need that.) I have played behind other people's backs, however. It's way easier, but since it usually happens when they rush for the exits, it's far less impressive.
