You can, but it may not be the best place for it, just in case anyone opens the door on you! It’s best to stay safe and only mount a suction cup vibrator or dildo to a secure surface such as a wall or floor. You can also attach to glass, but again, be careful as you don’t want to break anything from too much enjoyment. A popular way to use suction cup dildos and vibrators is in the bathroom as there are usually plenty of smooth surfaces to mount against, just be sure not to get anything wet that has batteries in!