I fell on top of a fic with Rodney McKay in an adult diaper and frankly, I may never sleep again.

... would now be a good time to point out that, given the state of Rodney in "Shrine", he was almost certainly wearing a diaper in canon? :D We just never actually saw it, thank all that is holy. (And the scene in which he discovers this is a missing scene that SHOULD NEVER BE WRITTEN, I'm just sayin'.)