Urinating in an open container
while riding in a moving car. The phrase originated in 1835, when settlers riding the Oregon Trail
were forced to relieve themselves in a large Stetson
hat, to avoid stopping their wagons for fear of Indian attacks.
"Geez Jimmy, would you drive a little smoother
? I'm filling up the stetson
right now, but since you're driving like a maniac, it's splashing