3 years old and no #2...

Hi Folks, I'm sure this is a common problem, but Thomas is my oldest & I'm not sure how to handle this. Thomas turned three last month. He has been going #1 in the potty for over 6 months, with no problems. However, he has yet to go #2 in the toilet. What worked for you, to encourage your child to go #2 without stressing them out? We have a friend whose daughter had a bowel obstruction, due to holding it in for so long... Another detail about Tom's personality -- bribes (toys, stickers, candy) DO NOT work for him. He could care less if you offered him a sticker to go potty. It just doesn't seem to bother him to have dirty underwear once or twice a day. He just careful walks over to me, tells me he pooped... then we go to the bathroom, he carefully steps out of his underwear and rinses them in the toilet. He hands me the underwear and even wipes himself. We've tried having him sit on the toilet after meals, even reading books and hanging out with him, hoping he will have to go. Inevitably, he will wait it out -- and then soil his underwear the second he is wearing them again... So -- what do you expert mommys and daddys suggest?? Thanks in advance for your help...