"Through the Looking Glass".
Sisko has sex with Mirror-Dax while pretending to be Mirror-Sisko. That's rape by deception, IMO.
Based on the realistic documentary that is James Bond, spies are completely forced into this, bending over backwards to serve queen and country by getting their end away, all in aid of not blowing their cover and ensuring the mission isn't compromised.
There's no pleasure in it, there aren't any double-entendres to be made, just professional, mission accomplishing sex.
Sisko had to completely become his mirror self, because a man who turned down an offer of sex would be immediately suspicious.
Besides, it was the Mirror Universe, it doesn't seem like Jadzia had too much of a problem with, one slap was enough to give him a message the next time she saw him.
Benjamin must've been goooooooood.....