This is actually a very common occurance for Foremans. What happens is the axle tube fills with water and over time deteriates the axle. I've heard of it happening with stock tires. I'm sure however that the laws accelerated it.
I too heard there was some metal obstructions but that's not what caused this. I got into a mudhole on the highline and gave it the gas and I heard "snap". At first I thought it was a CV but then the Foreman leaned way left and to the rear. It was then that it became evident what happened. The bad thing is right before I plowed into the hole, my buddy made some derogatory comment about Honda's. That was not the best time to break lol.
I priced the axle and it is only $116 new. I'm sure I can find a used one somewhere cheaper, if not, it's not that much.
Once I finally got it to hard ground and was able to ride it, you should have seen some of the looks I got. It was quite funny. A buddy of mine thought it would be funny to drag my wheel behind him hooked to a strap. It was kind of humorous. I did learn however, that you can not drive forward up a hill with three wheels. I had to drive in reverse for about a half mile. That was difficult.
Nonetheless, I still had a good time.
You play, you pay!