Who knows if the goodbye gesture is waving left and right or up and down?

Good-bye gesture, everyone is used to waving with his right hand instead of his left, not up and down, but left and right. Waving up and down indicates luck, just like a lucky cat. The left and right hand gestures indicate goodbye. Of course, if you say goodbye to others, you can look back up and down. It's nobody's business, because it's just an agreement, so that what you do may be understood by everyone and know what you mean.