Calling a captain over like you're backing a lorry in to a tight space.Don't meant to hijack this thread but very much related. Thing of other commonly accepted non lotg signals. I have mentioned a few already.
Upside down wiper: offside
Rainbow back and forth: coming from offside position to get involved inside
With the whistle
There long peeps: full time
Two long peeps: half time
Two or three short peeps: to attract attention usually ball not in play
Anything else?
No longer used but flag across the chest to indicate penalty.
Round circular motion indicating player won the ball