A Shang-High-Five is when someone steals a high five that was meant for someone else.
Stan: Hey dude that was an awesome bro thing you just did!
Bob: Thanks, bro.
Stan: **Puts up hand for a high five**
Bob: -Recognizes hand for high five is put up-
Fran: **High fives the SHIT out of Stan's hand before Bob can**
Fran (screaming): You just got Shang-High-Fived!"