Stoker left stranded by unexpected acceleration.
Two of my brothers were having a freezing overnight journey down the A1 on a BSA Bantam when both were in their teens. After a warm-up stop, brother 1 shouted to brother 2 to get on, now that he had finally got the clutch to work again, let it out and was a fair way down the road, marvelling at the improved handling before he twigged what had happened and returned to find brother 2 in the same pose as the photo. Happy days.