Re: @Ledswinger -- Opportunity Knocks...
It's idiots who don't wear underpants.
I agree, sounds bizarre. I suppose these people also don't use bog roll, as the carelessly trimmed fabric edges on the inside of a typical pair of jeans would go a good job scrubbing an unprotected nipsy. After a few days use those jeans might be a bit, well, musty, but I suppose the glamour of going commando has its own unique price.
You know how old pants get farted out? I presume that's the hydrogen sulphide reacting with some sweat to form sulphuric acid, but if you're depositing neat clag on the jeans, is that going to rot them through in no time? Have you seen the price of a pair of Levis?
Post script: Don't read this post whilst eating your dinner.