FinnAir hasn't done this in a while, but used to have a Flight 666 to HEL. Their hub airport is Helsinki so every flight is either to or from there. Usually they'd do that around #FridayThe13th or Halloween. The flight was popular among people who wanted to say/brag they flew on it. https://www.flightaware.com/live/flight/FIN666 #aviation #avgeek