Group forms a circle (minimum 7 people needed). One person starts off with a ball and throws it to someone anywhere in the circle. Someone catches the ball and the people either side of them have to put their inside arms up without hesitation. If there is reasonable hesitation that person has to sit down. Continue on. When the ball is thrown to someone where a person is sitting down beside them, then the next person standing has to put up their inside arm.
The game ends when there are two people left.
It’s a concentration game that gets a few laughs, especially once most people are sitting and only a few scattered people are standing.