Rule 12, Section 3, Article 1 of the NFL rulebook covers unsportsmanlike conduct. It is defined as follows:

There shall be no unsportsmanlike conduct. This applies to any act which is contrary to the generally understood principles of sportsmanship. Such acts specifically include, among others: 

(a) Throwing a punch, or a forearm, or kicking at an opponent even though no contact is made. 

(b) The use of abusive, threatening, or insulting language or gestures to opponents, teammates, officials, or representatives of the League.

The rulebook also lists several other unacceptable acts covered by unsportsmanlike conduct like taunting, contacting a game official, removal of helmet, disconcerting, lingering, hide out, leverage, leaping, goal tending, and freezing the kicker. 

I mention this because Denver Broncos pass-rusher Von Miller was flagged for unsportsmanlike conduct near the end of the Broncos' Week 3 game against the Bills for pulling the "too slow" move on Bills quarterback Tyrod Taylor, and I'm not entirely sure which part of the unsportsmanlike conduct rule covers "too slow."

That move cost the Broncos 15 yards and, eventually, three points. (The Bills' drive ended with a field goal to push their lead to 26-16.) This seems like an utterly ridiculous penalty to begin with, but it's even more so considering both Miller and Taylor were laughing throughout the exchange. 

Afterward, Miller admitted it was not smart move on his part -- shouldering the blame for loss because of his lapse in judgment. "I killed the game today with that penalty," Miller said. "I just have to be better than that and I will be better than that."

It seems like a pretty safe bet that we'll be hearing about this from the Broncos after the game.