Yellow Whatchamacallit

Show this thingamajig to an Englishman or an Aussie bloke and he wouldn't have a clue what it is or what it's used for.

A strange thing that I've noticed about this thingamabob is that it always come in yellow. I suspect that the manufacturers must have taken Henry Ford's famous quote to heart, "You can have it in any colour so long as it is yellow".