If you do it, you're a complete wanker (at that point in time only, not permanently).
Some of the main reasons why not are:
You have just directly influenced the play, therefore messing with the "one player to a hand" rule.
It's up to the individual players to notice things for themselves and act accordingly.
You might just put my girlfriend on uber tilt so she hits the wrong button and folds (which IS actually pretty funny but you should have heard her go off).
"Everyone does it" is NOT an acceptable reason, because anyone with any respect does NOT do it.
PMS is not the reason that people get annoyed with these things.
I would accept the appropriate ban for clocking the person who does it in a live event, but that's just me and that probably should be frowned upon
P.S. I had to make her a cuppa just to calm her the hell down
P.P.S That's not entirely true, I did not actually make her a cuppa. She is still cranky.

