The other reason I asked:
My CBR100RR was supposed to be track only, but I like it too much to only use it half a dozen times a year ... I'm going to Laguna Seca in a couple of weeks and numbers are required. My bike is black and white (bought from an ex cop) and inspires thoughs of "police bike": the last track day I did, the photographer labelled my pics "CBR1000 Popo" lol.
So I'm not quite brave enough to put on the number 911, because I figure that would have cops pulling me over constantly. But I bought 999, since that is the emergency number in Britain, and it's bound to make a few Brits giggle.