I do this!
To make matters worse I often dance around a bit too (exceptionally badly) - and recently was spotted (at low speed I should mention) actually playing a harmonica. (Also badly.)

As a result, I am:
1) Never taking a harmonica in the car again (temptation too strong)
2) Getting rid of the convertible (my in-car habits are too embarassing to be shared).
( superstoater is so mauve, you don't know what he's planning, Sat 5 Jun 2010, 22:38, Reply)