Not taunting? Idk I remember John Kelly got flagged for it once.
It's been called with Horns Down before too (directed at the crowd) when David Sills did it. Under some auspice of "intimidating the crowd" and putting the spotlight on himself...
Basically it's all about intent...length of time...probably after a TD when everyone is looking at just you doesn't help.
This is how the B12 refs describe it anyway...using "probably"...
Directed at crowd and short - probably not a penalty
Directed at a player or for an extended time - probably a penalty