The trouble I have with this cute idea is that it also applies to time travellers, interdimensional visitors and minions of the Illuminati. Every few years some bright kid realises this and places an ad in a newspaper asking someone in the future, after time machines have become commonplace, to zip back and meet him (I've never heard of a grrrrl doing this) in the public square at midday on Jan 1, or whatever. To the best of my knowledge, this perfectly plauible strategy has not even led to abduction and anal probing at the hands of chrononauts. But maybe the kids get painlessly xoxed and the originals are released back into the wild.
Damien Broderick