SOS! The string "Three Points - Three Strokes - Three Points" (without spaces) is the most well-known Morse signal.
In the vernacular, the international telegraph radio emergency sign is translated as "Save Our Souls" or "Save Our Ship". With the sinking of the unsustainable TITANIC, the emergency call sign gained notoriety when the ship radio desperately sent "SOS" and any help came too late.
"MAYDAY" - a day in May?
The emergency signal for international radio communication is "MAYDAY". Of course, this has nothing to do with a day in May. It signals that a naval or aviation vessel is in serious condition and urgently needs help. The word "MAYDAY" is not, as usually assumed, of English origin, but comes from the French. The original form was "M'aidez" ("Help me"). Only later was the term anglicised. Not only professionals, also every radio amateur should know the international emergency signs and emergency calls. By the way: According to Article 145 of the Criminal Code, their abuse in Germany is punishable.