Any object inserted within one of the cavities should be carefully monitored. Dirt and bacteria and seep inside the cavity causing problems for you and your sub. For instance there is a disease that can occur, can't remember the name, that is commonly associated with the vagina. It mostly occurs with tampons being left in the vagina for too long of a period without changing. It can also occur with dildos and vibrators. So you can keep it in but make sure to keep it clean.