What's the story here?

My own thoughts on this awkward situation:

1/ they are both really, really shy
2/ they are both on blind dates, neither realising that the other is the 'date'
3/ they are married
4/ he is sending secret messages to MI5 HQ and doesn't want to be overheard
5/ one of them smells
6/ she's had enough of his Blackberry
7/they are pretending to be teenagers who text each other despite being in the same room
8/ they are both bicycle thiefs trying to look innocent as a Police car approaches
9/ none of the above

Any ideas?