Is there a particular reason that EasyJet uses U2 as their code? Does anyone know why EasyJet uses U2 as the prefix for flight numbers? Other airlines have more logical prefixes. Eg. KL -> KLM, AZ -> Alitalia, BA-> British Airways, etc. Even though they do not always match the airline name exactly, they do mimic the name.
Easyjet got their IATA code fairly late on, and as such could not use EZ (which was in use by Sun Air), so they were randomly issued their IATA code of U2.

They do have the three letter code of EZY, just as British Airways has BAW as well as BA.