Apologies for any weird translations on the mahjong terminology or if I got anything wrong.
I remember being a kid and doing the same stuff that the Foremen did. When the adults were taking a break, we all gathered around the mahjong table and played with the tiles, making towers and playing jenga.
Cheating and miscalls in Mahjong...I suppose it would annoy your opponents because it disrupts the rhythm and flow of the games. If you're outright cheating then it'll make you an unreliable playing partner which would exclude you from future games.