My '03 FXD is named SWAMPIE because of all the violent thunderstorms she has taken me through.
My '04 Ultra is named SLEEPIE because of her propensity to lay down and take a nap on the side of the road occasionally.
My wife's '06 883L is named MISTIE because the day she purchased it, it was misting out and I rode it home for her in the light rain. (I wanted to name it satan or lucifer because she purchased it on June 6, 2006 which is 6-6-6). She opted for MISTIE.