Well it was meant as a serious question as I want something that was cheap and could kick around in the seat bases until needed. So well done for those that have supplied links and Idea's.
But I must say lads, I'm finding all your comments very amusing
Perhaps Poncho's would be a better Idea as you only need to cut one hole in the middle
Another Idea would be to buy a car cover and cut 4 holes in it? like a group poncho, that conjures up all sorts of thoughts
