I worked in aviation for 40 years and we joked about what the most USELESS things in the world might be:
- Runway behind you
- Sky above you
- Fuel in the bowser
- ........complimentary letters from the company!!!
All admittedly only applicable when the s..t hits the fan.
In motoring terms maybe - the spare wheel in your garage might compare.
(never used a can of goo but would hate to have to try it for the first time on that dark, wet, busy bend when you get the flat Give me the spare wheel any time)
