In the new Star Wars films, British actor Ewan McGregor plays Jedi master "Obi-Wan Kenobi." His brother, Colin McGregor, is a pilot in Britain's Royal Air Force (RAF). While the RAF, whose motto is "agile, adaptable, capable" is obviously a very serious outfit, they also have a sense of humor.
Colin McGregor's aviator nickname plays off his brother's character's name. It's is "Obi-Two." It turns out nicknames are fairly common amongst pilots - in the RAF, the American Air Force and others. Some more notable ones have been "the Mad Major," "Polly," "the Red Baron," "Spuds," and "Cyclone."