What diaper?

Thad was playing Mr. Fix-it somewhere else this morning and was fixing a broken pipe and they (who had the broken pipe) watched the boys while he worked. Thad fixed it and then they went home for naps, but when Sammy woke up I went to get him and he was all wet (his clothes were pretty much soaked from his midsection to his toes) and I thought, "wow, he really peed through this time." The thing is to "pee through" you actually have to have a diaper on, and well, when I took his pants off to "change" his diaper, there wasn't one! I thought that maybe he'd taken it off in his room, but no diaper there, checked the car, no diaper there either. Where in the world is Sammy's diaper? The only thing that Thad can think of is that Sammy asked to use the "big boy potty" and they took him to try--maybe they didn't stick his diaper back on--Who knows?! I for sure don't know where the diaper is, but I do know that a big sippy cup full of milk and a 2 hour nap makes for a really, nasty and wet 2 year old and a REALLY smelly, wet bed! P.S. I still haven't located the infamous missing diaper...