"Or we could do things at the party we've never done at a party before," Sirius countered, "and I can add them to my map." The map was a source of some contention between he and Remus. Similar to the map of Hogwarts which the four Marauders had wrought during their time at the school, one which was able to trace the movements of anyone on it in close detail, Sirius' map was designed to mark every place where he and Remus had once made love.
Which meant that it contained a whole lot of places, and a whole lot of information which Remus Lupin was not exactly thrilled that anyone else might learn about them, being a rather private sort of man. Unlike his lover.
"What a wonderful idea," Remus, he concurred, nuzzling Remus' neck joyfully, "and how thoughtful of you to mention it. What do you think we should wear?"