On the bottom right hand corner of my dash near the door there’s a switch with EXT marked on it, when I switch it on a little EXT sign comes up on the dash and nothing appears to happen, this is on a 2005 R420.
Anyone know what it does? Even the drivers handbook that came with the truck doesn’t tell you 
press it and it turns on a homing beacon for EXtra-Terrestrials, after a few minutes you will see bright lights and then be beamed up to a waiting spaceship, lots of things will happen while they experiment on you and for you time will continue, but when you return to your truck time will have stood still 
It’s the Exterminate switch, press it and all lesser trucks, i.e DAF’s, Volvos ect, in your way are destroyed.
switchlogic:
It’s the Exterminate switch, press it and all lesser trucks, i.e DAF’s, Volvos ect, in your way are destroyed.
And you should know 
Well its there to illuminate the light on the display whilst switched on - simples