I heard about that happening to a little boy a few weeks ago. It was on the internet news - Fox and CNN.
Anyways, he had been swimming and came home with water coming out of his nose. He went to bed later that night and drowned while he was in bed because he still had water in his lungs. I think the medical term for it is something like "secondary drowning".
Not like I’m trying to scare you but do be careful.