Dog question (minor TMI)

Why does my 4 year old Pug get a boner everytime he rides in the car? He doesn’t stick his nose out the window like other dogs. He really doesn’t like riding in the car at all. He wimpers a bit, and then just sits on the seat and gets a big stiffy. He’s fixed, and he never walks around the house with a woody. Only in the car. Nowhere else. WTF?:confused:

Good, good, good…good vibrations? That was always my guess. My dog will get erections at the oddest times, too. And he whimpers in the car.