According to Jeremy Paxman it's an old printers' term.
Are you calling Paxman a cunt?
( Dr Preference AjcuiVd289, Wed 22 Jun 2011, 9:16, archived)

sure, why not
www.phrases.org.uk/meanings/dog's%20bollocks.html (this one supports what binky said and what you said)
www.phrases.org.uk/bulletin_board/43/messages/1022.html (this one debunks what i said)
( manolith hooray for me, Wed 22 Jun 2011, 9:25, archived)

it's a good myth, though.

( sleepybinky, Wed 22 Jun 2011, 9:47, archived)

female moths all look the same to me

( manolith hooray for me, Wed 22 Jun 2011, 9:53, archived)