ALWAYS rode in the back of the pickup.
Sat on the axle of Dad's Oliver when he was listing corn, facing backward, and manipulated the row markers at the end of each round -- pulled a rope to lift one side, eased the rope to drop the other. If I'd slipped off, I'd have been killed by the shovels before Dad knew I was gone. I was 9 or 10.
Marked for the aerial crop sprayer by standing on the row he was supposed to spray next, got soaked with whatever it was he was putting down.
Ironic thing about this is that Dad was a lot more protective of me than were the fathers of my friends. I wasn't allowed to drive a tractor by myself until once or twice when I was 12, wasn't allowed to go hunting (BB gun doesn't count) without him
The practice of standing or sitting on the axle of old tractors, also listed by Art in this thread, is the real mind bender to me. That was SO common, and probably still happens, and yet so dangerous. A slip or a trip and you are getting run over by the trailing implement. Yikes!
We also rode in the back of the pickup trucks whenever we could and at least one stupid time, we let our feet drag on the gravel below us as we sat on the end of the downed tailgate. The notion that our heel could catch, etc, and we could be pulled off barely occurred to us idiots.