I'm just surprised nobody's been challenged to a friendly game of ping-pong here. That IS what the paddles are for, right?
Have your sub open as wide as they can to take as big of a bite as they can out of an apple. Their teeth will bottom out, and they won't be able to close their mouth. Use the apple as a gag, like on a roast pig.
Blindfolds used for travel? The elastic wears out, but can be replaced with a shoelace.
Ever try to hold in an enema for a long time? Use a bit of lemon juice to increase the cramping.
Ice cubes in all the wrong spots is also a very cheap erotic torture.
Take a trip to the Salvation Army or the dollar store with an open mind.

- Bracemaiden