Don't get bored-visit Wal-Mart and let your imagination soar...
In the sporting goods department, check out the Cutter snakebite kit. Throw away everything inside, since we don't treat snakebite by constriction and suction any more, but keep the three yellow suction cups. Two of them are nipple sized, and there is a third inside just right for pulling on a clitoris. My favorite part is to make the victim lick and suck her own nipples first, to get them wet and ready to form a good seal, then watch her tremble in anticipation as I squeeze the cups flat and position them just right, before releasing them to a gasp of sharp pain. They don't hold all that tightly, not enough to do any damage, but they are uncomfortable over long periods, and of course when they come off, you just put them back in place.
Next time, in the housewares aisle...