about 1 1/2 years ago, matt flushed a pair of underwear-they were tiny and it didn't even clog it (surprised me) and i was told by the plumber they had a good chance of making it out to the sewer system and/or crumbling apart in the pipes until they were totally gone. however, recently one of the boys clogged the toilet and we had to have a plumber snake it out. It cost us $180. which stunk. good luck. is it clogged? did you try snaking it yourself? you can ( i think hardwares have snakes), and get results if the diaper is still caught close to the toilet.
Re: has your DC ever flushed a diaper down the toilet?