C.Z.
Hi T.,
In my childcare, I have experienced this problem as well. Looking back, it is right around the same time (20-30 months of age) so this doesn't surprise me. What I do, for obvious safety reasons, is check the "food-holders" mouth before I put them down for nap. I make a big game out by saying "Let me see everyone's empty mouths!" I do this several times throughout the meal. Everyone opens their mouths and when I see that it is empty, we all clap and give a big whoop. Yes, I know this sounds silly, but my main concern for these children is choking on the "hostage food" during naptime! I make sure the offender has a drink at the end of mealtime and then I ask for empty mouths, once again. I have even been known to offer a little dum-dum sucker to everyone who has an empty mouth at the end of mealtime. Some people say no bribing, but I am more concerned for their safety than giving them a sucker as a reward. This stage doesn't last long so don't worry about it.
Good luck and let us know how everything turns out!