Hang up Christmas lights indoors? Hmm, that's a good question. The key is to make sure you have enough space and that the lights are hung securely. You can use hooks or nails to attach the lights to the ceiling or walls, but be sure not to damage any surfaces. If you're hanging lights around a door or window frame, make sure they're not blocking the way or causing any tripping hazards. And of course, make sure all the lights are plugged in and working properly before you turn them on. Have fun decorating!