For example, the Middle Eastern hand gesture for "stop" is totally different than American hand signals. The confusion probably caused at least a few of the hundreds of Iraqi civilians shot at traffic checkpoints by US soldiers. https://savageminds.org/2008/09/28/how-not-to-signal-stop/
> 5 / to bring one’s hand toward one’s mouth without quite touching it Modesty. A gesture of eloquence employed by the great orators of antiquity.
AFAIK, this is the wrong explanation. The gesture is still in use today in Italy, and its meaning is different.