Two of my all-time favorites:

"Get the f##k off the road" - screamed from a car in the far right (his direction) oncoming lane, on a 6 lane roadway (so there were effectively 4 empty lanes between us - plus a turn lane or two for good measure).

When I was battling a series of 10 flats over a 2 week period (ditched those rims and tires) - I had my last flat and stopped, called for a sag pickup and waited. Over the next 30 minutes or so, a group of teens in a car kept rolling past me screaming "QUITTER!!!!!" out the window - it made me mad the first time, but then I laughed each of the next 5 times they cruised past.

"QUITTER!"