I once saw a school bus driver swerve his bus in front of a car that was passing him WHILE KIDS WERE STILL ON THE STEPS OF THE BUS. I reported him to his school district.
What you needed to do with the ice cream man was get out and start putting the ice cream in your cooler, and yell "Thanks!"
You do have a cooler in the back of your pickup, don't you? All true Texans have coolers in the back of their cowboy caddilacs, just in case they come across really fresh road kill and stuff.
I don't know of any state law against passing stopped vendors.
