This is best played on a small table or even a kitchen island would work, something with clear edge boundaries. 

This is played with two players at a time. With a coin or die you will assign each player to either Mitt or Tongs. Players will stand on either side of the table, one with the tongs, one wearing the oven mitt, with a marshmallow placed exactly between them. When the games master says "go", the player with the Tongs will attempt to grab marshmallow. The player with the Mitt will attempt to swipe marshmallow away before they can grab it. Mitt can only cross the edge of the table into the play area once the tongs have first crossed that threshold. Tongs win if they grab the marshmallow, Mitt wins if the marshmallow is swiped off the table before it can be grabbed. If the Mitt strikes too early, the Tongs win. If Tongs fail to grab or drop the marshmallow, the Mitt wins. 

Scoring is, as always, completely arbitrary, you can award the winner any number of points you wish. Decide how you wish based on the number of players.

There really isn't any way to make this one better. Tongs win more often than not, but it is very possible to win with the Mitt, especially after practice.

Feel free to use something other than a marshmallow.