I lost a bet and have to wear diapers for a week. How do I avoid getting a rash?

I was so positive that the capitol of Illinois is Chicago, so I made a bet with my friend. I thought she was going to have to wear diapers for a week and it would be really funny. Now it turns out that Springfield is the capitol of Illinois. Chicago isn't the capitol of anything! The rules of the bet were that I'm allowed to change whenever I need it, but I have to "do my business" in the diaper. I know that you deal with this sort of thing because you have babies. I'm bigger, but I think that the rules of skin care are about the same, so I thought I'd ask you. Please tell me what I should and shouldn't do. (Besides making bets; I've learned my lesson about that so you don't have to tell me.)