Thanks S.o.S. for the comments and all of you.
One very good piece of advice come for Slot him/her self about people barely making the high-level frequent mile program and behave like they are the most knowledgable pax on earth and there are others they qualify in no time and are so humble they will not even ask for an extra glass of water if the crew is too busy.
Also my advice is a bit practical: as during the meal there are many covers and detritus. If the seat next to me is empty I open a vomit / waste bag to throw what I don't need - not food I love airline food. The bag is given to the crew after they take the trays away.