Nitrous oxide dispenser, used legitimately in making whipped cream.
I'd urge considerable caution to those who see this as a recreational drug. Be sure that, if you use it to induce unconsciousness or even get close to that state, you can get away from the gas. My 19-year-old son died by filling a plastic shopping bag with NO2 from a Whippit and hanging its handles over his ears while lying face down in his bed. He passed out and suffocated. I found him dead the next morning.
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