For 2 players, each holds out their hands and grasps the other's as in the photo with their finger nails held against the insides of the other person's fingers.
Now both players squeeze as hard as possible (in a 'crab' like fashion) which forces their nails to dig into their opponent's fingers while all the time their opponent's nails are digging
into theirs.
The game is to see who can stand the pain and last the longest.
This is a game best suited for players with long (even better, sharp) fingernails. This is a game for tough people. This is a game for girls!
