Sack-tapping
Teenage boys are playing a “game” wherein they ambush each other with a punch to the nuts. It’s called “sack-tapping,” and was supposedly made popular after a 1998 episode of South Park.
New Definition: “Any painful insult that surprises the receiver.”
Usage: “Dan got sack-tapped in yesterdays creative brainstorm and just walked out for lunch”
Further reading: MSNBC, Jezebel