I've never seen it specifically prohibited, but should something unusual happen, you'd be in violation of 14 CFR § 91.13
eCFR ? Code of Federal Regulations
§91.13 Careless or reckless operation.
(a) Aircraft operations for the purpose of air navigation. No person may operate an aircraft in a careless or reckless manner so as to endanger the life or property of another.
(b) Aircraft operations other than for the purpose of air navigation. No person may operate an aircraft, other than for the purpose of air navigation, on any part of the surface of an airport used by aircraft for air commerce (including areas used by those aircraft for receiving or discharging persons or cargo), in a careless or reckless manner so as to endanger the life or property of another.
Remember, nowhere does it say that the gear must be down for landing either...