"Mandy Rice-Davies applies", from one of the quotes of the Profumo affair in Britain in the 1950s.
When it was put to her that someone had denied her allegations, MR-D said, "He would, wouldn't he?"
For as long as I can remember, it's been a common response on cix to, for example, Geoff Hoon denying anything was his fault, ie total disbelief of what someone's said. But it can also be used when pointing out someone has a (often undeclared) interest in the outcome of something they're disputing.
[cixen: it'd be interesting to do a search to see who said it first and where they got it from.]
Clearly, it's not that common an acronym outside 🙂
While we're mentioning Hoon, anyone want to bet he has the full confidence of Tony Blair in a fortnight's time?