Real fits and TSA

Hi,
Does anyone have any solid experience about trying to go through TSA wearing Real Fit underpants. I have a very early flight coming up and suspect I will sleep on the plane. I don't want to have a problem if I get scanned. I also don't want to fall asleep and pee my pants on the plane. I don't want to make a big deal out of it as I am traveling with people I don't know all that well. Any advice will be very appreciated.