I know a guy that carries one.. Its actually pretty good for a lunch stop in bad weather, but I wouldnt bother personally..
As for other weird stuff. I saw a guy going up Lochnagar in a suit which seemed odd, with dress shoes & everything..
But the weirdest thing I have come across is a cheeseboard set up on the Ben Alder trig.. 3 types of cheese and little packs of crackers, with a rather nice penknife left to use for the cheese.. It was atrocious weather, but as someone had gone to the effort I indulged and it was rather tasty
Because the weather was so atrocious, I revisited the summit a couple of days later after doing the ridge next door in glorious conditions. Cheese was all gone, but I rescued the knife and it still accompanies me on all my trips.