Why not allow the children to raid your wardrobe, dressing-up box and linen-cupboard, then go to town with make-up and accessories, hats, scarves, gloves and glasses (you can give them a theme, or let their imagination run wild).
Once they are in character, encourage them to make up a play and film the results. Some of the funniest home videos are made during intense boredom! And they make for excellent viewing on the next rainy day.