My hubby and I were just joking...I guess the "dumb thing that boys do" phase never really ends????? With that said, my son swallowed a quarter when he was 3. It got stuck in his throat. Had to get an x-ray. The x-ray was taken several hours after he swallowed it and the quarter didn't move. So we had to take him to Childrens Hospital to get it removed. They put him under and used a small camera and tiny prongs to try to get it. But the air that they needed to get the camera down his throat opened up his throat just enough to push the quarter down to his stomach :(. So they couldn't grab it. For two weeks we had to search his poop because they were worried about the quarter not passing through and oxidizing in his stomach. We never found the quarter but x-rays never showed the quarter again.
But he was 3, so I would guess that your son being much bigger, it should pass alot easier.
And then just for kicks...three weeks after the quarter incident my son was back in the ER because he stuck my keys into the electric socket RIGHT after I told him not to do it. Same as the quarter incident, Mommy said to put the quarter down, then he swallowed it. Then about a month after the socket incident, he dropped a big clay pot on his foot in the backyard (right after Grandma and Daddy both told him not to pick it up) and had to go back to the ER to get 3 stitiches in his toe without any type of numbing medication. Oh the dumb things boys will do "just because" :O.