Crossdressing
"You want me to do what?" Sirius stares at Moody in disbelief
"Pretend to be a woman, for the evening," Moody repeats. "Like I said, men are weak towards seduction, so we might get a few loose tongues wagging if you do as I say."
"Uh, there are couple of holes in your plan," Sirius says. "What if a spy is a woman? And why can't you employ an actual woman to seduce the men?"
"To answer your first question, I have thought about that. You're not the only one I've coerced - I mean, asked - for assistance in this matter," Moody says. "As for your second question, I could, but it's more fun this way."
Sirius groans. Trust someone like Moody to combine work with pleasure. And there was indeed work to do. Moody had asked Sirius to do this, and so Sirius was going to do it.
No matter how embarrassed he ended up being by the whole process.
It took a better part of the day to get him in a dress. It was a proper dress, with lacy frills and everything. Sirius felt like an idiot wearing it. His hair was let down in order to resemble a female hairstyle more. His cousin Andromeda took it upon herself to make sure it goes well. Moody himself stayed in the background, supervising the whole thing. He claimed it was necessary to make sure the whole thing went well, but Sirius suspected he was a covert pervert.
Finally, the preparations were done. Moody and Andromeda had both declared he could pass for a decent girl. Now came the hard part: getting the male attendants comfortable enough to talk. He hoped that whatever unlucky soul Moody had picked to do the same to the female half of the soiree was good at their job too.
He didn't count on dealing with a particularly lecherous attendant, who kept him over their knees for approximately a quarter of an hour. He could have sworn he heard several camera flashes during that time.
Finally, he managed to escape and join the Marauders, who had appropriated a separate table for themselves. There was one empty chair and Sirius slid into it, with a grateful look on his face.
"So did you discover anything?" Remus asks.
"Nope, not a thing," Sirius says. "Some of the men did talk, but I couldn't find out anything useful. I suspect that Moody orchestrated this simply for his own amusement, however. He seems insistent on catching the spy, so here is hoping that his methods pay off in the end."
"I toast to that," James says exuberantly.
"Me as well," Remus nods. "The evening wasn't completely wasted, however. You make for a great girl, Sirius. I even managed to take some pictures."
Peter follows suit, of course, and raises his glass in silence.
"Wait, that was you?" Sirius scowls. "Give me the camera, Moony!"
He reaches out to grab it, but Remus pulls it out of his reach.
"I am not letting you destroy them," Remus says firmly. "I want to treasure them forever."
In their excitement, none of them notice that Peter had let out a relieved sigh.