Bottle/jar grippers

The Hot Pepper

This little kit works a treat. The conical for growlers and bottles, the others for salsa, hot sauce etc.
Pressurized growlers are a pain, this red one opened it with ease!
The Hot Pepper said:
cuz don't want beer on the floor?
I failed to get back to this before now, so sorry. I don't mean to turn the bottle upside down, but the can opener. Fit the tip under the edge of the bottle cap, then gently press the lower part of the opener towards the bottle. This should release some of the pressure but, if not enough is released, move the opener over a bit and do it again. Then the caps come right off by hand. The key is to only release a little bit of pressure at each point, so the cap can still be used to reseal the bottle, if needed. Don't press hard enough on any point to warp the cap. This works on a variety of cap types, as well as screw-on lids that are more stubborn. 
Pressurized growlers don't work like beer bottles... and the lids are plastic, but the contents are pressurized using a 2-step process where a nipple is put on the growler to fill it with CO2, then beer is filled up and the gas stays under the liquid which pressurizes it when they put the lid on, and makes it hard as hell to open.
Admittedly, I am not a beer drinker and have never opened a growler. But I've loosened plastic lids this way, as well as metal, so suspect it could work. Dunno. Maybe I'll find some thirsty folks one day and see if I can open a growler for them, by one means or another. They can have what's inside.... as long as they don't mind shards of glass,  if it comes to that!  ;)
Well the little cone shaped red one they sent is perfect for growlers. So I'm set.