Seen in the Salt Lake County Code of Ordinances, § 10-64-010, as well as in several other Utah local codes:

It is unlawful for any person to discharge any firearm, gun, sparrow gun, flipper or similar contrivance within the limits of the county except in a careful and prudent manner, and in such designated area as the council shall by proclamation appoint.

What in blazes is a "flipper," in the sense used here?