Being without a proper bottle opener brings out the creativity in people.
Bic lighters are good and if you open them quick enough they pop like a champagne bottle. Completely safe unless you push into the bottle with the lighter while opening like I have seen some people do and take a chunk of skin out of their knuckle from the cap. Lol..
I have a opener made out of some bike chain and a piece of bike cog for home, a key chain for while I am out, and an opener mounted on my mountainbike for refreshment after a long ride. Reef makes sandals that have a bottle opener on the bottom of the sole which I thought was cool but I already have enough bottle openers and enough sandals.
If somehow I am without an opener, I'll eventually figure it out and I don't complain. I have fun with it.