I make sure never to follow behind a semi with water dripping off the top. Seen some nasty results of that stuff flying off.
Loose crap in the bed of trucks should be added to my peeve list with left lane vigilantism.
On the other hand. I do get a kick out of these minivan and SUV (some cars even) drivers that leave the snow on the roof. After a few minutes of heating the inside of the vehicle driving around town, that sheet of snow now sits on a film of water. First stoplight and it slides right off onto the windshield.
WHITE-OUT!!
I have to laugh at those bozos.