PenPal.

PenPal is a service whereby somebody that you can vaguely remember writing to, as part of an "English Speaking Union" initiative perpetrated at your school by the geography/english teacher, is the father of a disfunctional family that turn up on your doorstep, from a far flung part of the English speaking world, with two appalling teenage daughters, demanding lodging. Subsequently, they ask for more food at meals, order extra dishes at restaurants, without asking you - criticise neighbours and your whole lifestyle and disappear none too soon.

....It happened to a friend of mine!