I was reading PoA whilst eating and got to the chapter where Harry is caught by Snape with the Maruader's Map. As you may recall, when Snape tries to find out what's on the map, it delivers personal insults to him, compliments of Mister Moony, Mister Prongs, Mister Padfood, and Mister Wormtail. Immediately, Snape calls Remus and makes him come over.
It's so clear that Snape knows and Remus knows Snape knows and Snape knows Remus knows Snape knows, but they just dance around it in a most controlled fashion. Partly, I'm sure, because they're in front of Harry, who is totally clueless, but I rather think they'd be talking like that even if they were in private.
There's so much not said, so much subtext, so much tension, Snape saying "Lupin" and Remus saying "Severus" and both speaking oh-so-carefully. They're incredibly well-matched for this sort of thing.
It brightened my day considerably.