The guy coming back from the vet with an injured dog in the back, or the lady who just picked up 25 potted plants from the nursery, or the kid trying to move his fish tank all probably think the same thing about you when you're riding their ass while their trying to manage a turn without spilling/hurting anything.
*I also get pissed when people do things slowly, but having been in all of the situations listed above, and more, I try to remember to give people a break since I don't know what they're doing.
True... which is exactly why I don't nudge & do grumble. ;-)