I'm North at table 1, set up this way so that I can "keep an eye on the room".

The almost silence is broken when North at table 2 blurts out "When you don't designate a suit I can chose which Jack you play!!!"
I leap out of my chair and skip over to the table.
East is playing a 3nt contract there's something like this left in dummy
Declarer has been running hearts from dummy and had simply called "Jack" on the 6th trick.
(which reminds me of some "A" players who simply nod and grunt")
I explain to East that the correct designation is by suit and rank however, when running a suit, rank only is common usage and prescribed in laws (46B3a).
I explain to North that he was incorrect and remind him to call the Director when there is any problem at the table.
As I leave he says "I wasn't going to make her play the other Jack, I just told her that I could!!"
Back to the table to explain that only if Declarer says "play anything" can a defender designate a card, 46B5.
Some people are going to have fun knowing this now.
Second call, there's been a revoke discovered a few tricks back in the play.
When I arrive at the table the players have 3 4 or 5 cards in their hand. The last 4 of the quitted cards in front of each player are in various orientations and positions on the table, everyone is talking at once and dummy is telling me what needs to happen.