My son turned 3 in January. He is potty trained during the day and usually running around without any clothes on the lower half. If we put training pants or underwear on, 85% of the time he has an accident. How do we get him used to wearing underwear?
Okay, it sounds like your son isn't quite ready developmentally for potty training...it is a milestone that happens usually around 3-3.5 for boys, so you are probably pretty close. But, he has to have 2 accomplishments first:
1. The desire to be clean.
2. The ability to sense the urge to go, and not just after he's gone.
The point he is missing is that humans wear clothing on the bottom half of their bodies and when they feel the urge to poop or pee, they need to remove the clothing in the bathroom and sit on the potty. Perhaps that is the first message you should work on (and put him back in diapers for now!)