I have no problem with the m'aidez or varients thereof as a trouble signal for aircraft.
That said, I remember that in late 1940s - at the end of WWII - May Day was taken over by USSR as a celebration of communism. Parades in Red Square and all that!
Then along came the lawyers and they started calling it Law Day as a counterpoint - the first time I heard of lawyers giving free advice was on call-in radio shows as a public service on May 1st to celebrate Law Day. That was in the 1950s.
Then I went to Hawai'i and discovered that : "May Day is Lei Day in Hawai'i." People give and wear lei. A contest is held for various types of lei and the entries are exhibited in a special area near the stage in Kapi'olani Park. They are magnificent. If you are ever in Hawaii on the First of May .... well ... lucky you!