Obsession with twngan

The second day was the longest day, not only in terms of mileage, but also because of the hilly, narrow, 5mph roads around the Hoover Dam in Nevada. Anyway, the fun of the day was neither the road condition nor whatever happened (and stayed) in Vegas, but the followings...

While driving in Arizona, there was this truck with a picture of a guy at the back, pointing his index finger upward. He was really annoying, given that as the driver behind him one has to stare at him. Luckily, the truck (as usually) was slow and could be passed easily. What's more interesting was after Kingman when it was close to Nevada, it was completely dark already. The smart thing to do, given the unfamiliarity of the area, was to follow another car. A pickup truck was used for that purpose. But wait a second... What was that grayish cloud-like thing on the pickup truck? That looked like... Casper! God knows why, maybe he wants to have some fun in Vegas too. But right before entering Nevada, Casper (and the truck) was stopped in a checkpoint by some cops (Why do they have checkpoints anyway? Do people smuggle stuff from Arizona into Nevada!?). Not sure what happened to Casper since then...