I had nitrous one time about 10 years ago. Friends of a friend had one of those devices where you could pinch the container and the gas would flow into a Ballon on the other end.

Just exchanged the air in my lungs with the gas in the Ballon until I kind of passed out for a second, followed by a wave of euphoria and laughter.

Was fun, but not something I would do again, even without the included health risks.