The line is silence!!!! Silence cannot be misinterpretated.
IMHO, the line would extend to some silent acts such as an act of pretended disgust by the QB toward a back who's pretending to be confused, etc,etc. I believe the drama team isn't formed until after the Fall sports season and those "talented" football players should save their skills until then.
IMHO, the list of unsportsmanlike acts with the intent of lulling the opponents that there's a problem and the snap isn't imminent is endless. These should be apparent to the officials in their pregame coaches meeting and advised then of their illegal nature. A barometer could be :
Would Knute Rockne consider this good football? .....If no, it's illegal.
Would Coach B of OUR

Patriots consider this good football?.....If yes, it's illegal

.
If I was a

coach, some distractions I might consider....
QB to D-Line : "Whew, the center just 'cut one' ,let's just back off and take a deep breath

"

QB then backs off,holding his nose...direct snap to tailback.
QB to D :" :!#WOW! The prom queen's clothes just fell off

"
QB rubs his eyes...direct snap to tailback

>
QB sneaks loaf of bread under his jersey

. Direct snap to tailback. QB pulls out bread, pretending he's going to pass

. As hungry D-linemen close in, QB throws them slices of bread

.
On the second thought, I don't think I'd want to coach...
