On the Chronicle of the Horse forums, you'll read occasionally about something called "the Inverness Problem." A member with the name Inverness once confessed about chafing in the nether regions, and it sparked a long, involved thread on the subject.I read it with interest, since the summer months can sometimes lead to chafing. There are several underwear products on the market -- you'll see them advertised in Dover Saddlery's catalog, but they are all expensive, running between $21-90, and who knows how long they last?
Now that I'm biking, I really need padded bike pants, but I hate buying one more pair of pants when I have so many yoga pants and leggings already. The solution was to find padded bike undies that work, and that don't cost a lot, and wear them under everything.
I found these on Ebay, from ilastone (seller), you'll find these great pink padded undies for under $8. They're light, well-padded, and cheap! When you think of the cost of a regular pair of underwear, they're a steal.