[alexander_busek]

There’s something called the exit bag where you put a bag over your head and pump in helium.

Nitrogen is cheaper.

But doesn't sound as funny.

Regards,

[Myrddin]

But doesn't sound as funny.

I suspect the party doing the bag over the head won't have an audience to enjoy the funny helium voice. In my air crew training classes, we were advised that upon decompression in flight that you have about 20 seconds of "useful consciousness" to act to get the oxygen mask on. The oxygen deprivation brings unconsciousness fairly quickly.