Leave it where it is, clean around it, buy him a nice bottle of lube, put a bow on it and a "From: [Your Name]" with a little heart or something to indicate you do not disapprove of his toy, and leave them together. Don't mention it to him. That way, when he goes to get it next, he won't have to wonder if you've seen it, how you feel about it, and then if he never brings it up then you don't bring it up either and it can just be a mutually understood thing you don't have to talk about but at least he knows he doesn't have to be embarrassed or ashamed. Or he will bring it up himself and you guys can talk about it, or whatever he wants. I think this is a nice compromise between playing dumb like you never even saw it (which is inconvenient, since you want to be able to clean/move it) vs respecting his privacy.