While in bed and under the covers with your significant other (or anyone else for that matter i guess...) let out a fart from deep within your colon. Next, rap the poor girl/guy up so they can't escape, forcing them to huff your ass gas. The more they struggle the better, as they will end up taking deeper breaths.
Techniques of the Dutch Oven may vary depending on the region your from.
The "Nightmare Surprise", indigiounous to the Helsinky tribesmen, is performed while their wives were sound asleep. This invokes the sublimal belief that they are being barraged with mustard gas in their dreams.
The "Bolivian Bat-Mitzmah" is one which you have your friend sneak into the room to fasten the covers, then you and countless numbers of your buddies bestow your "gifts" under the covers, officially marking her transition into grown womanhood...