I had the same problem with my 21 month son today. He moved to toddler bed 2 weeks ago (we need the cot for his little sister) and had only got out occasionally so far. Today, however, it took me a whole hour to get him down for his nap. I did the same as legalbeagle which was pretty tiresome but eventually he gave up the very funny "game". I think I'd been expecting this behaviour since we made the big bed move. Tonight we had no problem. Hopefully next time he decides he doesn't want to got to bed, he'll give up the game more quickly. Good luck.