Done It when I was young, yep. Do it again, nope. Cured me quick.
17 years old in the late '60s. Friend and me messing around in the forest perserves NW of Chicago where the C&NW freight line runs. Jumped in a open boxcar in a stopped train. It started up in a minute and my friend said I was an idiot if I stayed on. I decided to take a short ride. Didn't take long to realize that the next stop was Milwaukee. Jumped down a 10 foot embankment and came up with bloodied knees and elbows,and, a long painful walk back.
I may still be an idiot but I think I'll stick with Amtrak and the Museums.