OK, if you happen to have an extra-freaky fear of flying, and are a tad superstitious, never, ever board a plane designated "Flight 191"!
==> NASA X-15 Flight 191 (1967), X-15 experimental rocket-propelled test plane, broke apart in flight, killing its test pilot. One-hundred ninety-nine total X-15 flights -- only one was fatal -- Flight 191.
==> Prinair (Puerto Rican International) Flight 191 (1972), DeHavilland DH-114 Heron, crashed at Mercedita Airport in Ponce, Puerto Rico, killing five people.
==> American Airlines Flight 191 (1979), Douglas DC-10, crashed shortly after takeoff from Chicago O'Hare Airport, killing 273.
==> Delta Air Lines Flight 191 (1985), Lockheed L-1011, crashed while on final approach to Dallas-Fort Worth International Airport, killing 137.
==> Comair Flight 5191 (2006), Bombardier CRJ-100, crashed on takeoff from Blue Grass Airport, Lexington, Kentucky. killing 49 people. OK, not quite "191" but pretty close.
==> JetBlue Flight 191 (2012), Airbus A320, a flight from New York John F. Kennedy airport to Las Vegas, Nev. diverted to Amarillo, Tex. after the captain had an alleged panic attack, rambled incoherently about how they were going to die and not make it to Las Vegas, was locked out of the flight deck by the First Officer, and was restrained by passengers.
This is really just for fun (and a moment of perhaps spooky X-Files/Twilight Zone consideration...), but consider: plainly, some fears are totally rational (I'm afraid of eating mayonnaise that's been out of the 'fridge for two days). Some are totally irrational (consider your own examples...). Some are a mixture. Would any of you get on the plane if you realized you were booked on a Flight 191? BTW, most airlines have quietly stopped using "191" as a flight number. Rational? Who knows?