Now here's an idea for that beer-guzzling friend on your Christmas list - be the first in your neighborhood! I wonder if this patent was ever commercialized (I randomly happened on this patent). The link on this page will download the patent as a PDF.
A toy gas-fired missile and launcher assembly ... the operator places the inlet tube with its valve open adjacent his anal region from which a colonic gas is discharged... The ignitor is then activated to explode the mixture in the chamber and fire the missile into space.
Google Patent Download (PDF)