Been there, seen it,done it and luckily in my case, survived!
It caused me to open a thread back then "RA,to follow or not to follow"
In my case was a B767 operated under Italian FTL's therefore you can assume i was very tired!
SantaMaria cleared a Spanish A340 to climb into conflict from 1000 ft below, on converging course. I was awoken from my short power nap by my F/O who decided to include me in the scenario as other aircraft was 500 ft below and climbing. Resulting RA put me in a descent followed by the same action from the A340 as he realised the mistake and also descended, probably just as he got the climb command! I suspect that his action was also driven by his knowledge that he was about to infringe my airspace!
The resulting aerobatics will remain with me for life but, in this case we all survived!