That sounds like some sort of gang hand signage. The dimwit Latino and Amish gangbangers are always going around making bizarre finger signage that simply makes them look like what they are, dumb a-sh-les, to the rest of us.
It's not just dimwit latino and Amish gangbangers.
Imagine the discomfiture of a normal mainstream American family which discovers that their son is marrying a 30-something seemingly normal woman who, together with her childhood closest friends are flashing the moron signs at their wedding.
A lot more common than most of us realize. There's no explaining the clueless' attraction to the dysfunctional definition of "cool..."