Heh. The worst one we've heard was on a Greggs delivery van. It was in a queue of traffic for a T junction and signalling to turn left. Along with the flashing indicators was a stentorian voice announcing at 10 second intervals -
"WARNING..! This Greggs vehicle is turning left..! WARNING..! This Greggs vehicle is turning left..! WARNING..! This Greggs vehicle is turning left..!"
AAAAARRRGGGHHHHH..!!!!!