Toemometer - Pronounced "toe mom' ett er" and rhymes with thermometer for good reason. Some people are equipped with a toemometer, located in the big toe (and possibly other toes). Toemometers are used to check the water temperature in large bodies of water, such as swimming pools or lakes, while deciding if one should dive in.
A variation of this gift is the "moomometer," located on some people's inside wrist, often used to check the proper temperature of bottled milk before serving to a baby.
To explain toemometers, consider this example. Joe dipped his toemometer into the swimming pool, then turned to his dad and said, "The water's fine, let's go swimming."