Sirius laughed at the string of innuendo from Gaius, and wrapped an arm around him. "No lederhosen," he said firmly, "orange or otherwise Honestly, no orange, either. And if I help you, we'll never make it anywhe-- Oh!" He reconstructed that choice. "Help with transfiguring your robes?" For a moment, he just stared at Gaius. "You're the Hogwarts Transfiguration professor! You think I'll do a better job?"
On the other hand, Gaius had been having problems with his magic, recently. Sirius had too, but nothing so severe as ending up half-dog. He started to draw his wand, but then thought better of it.
"No -- old fashioned way it is." He turned Gaius towards the stairs and gave him a friendly slap on his robe-obscured arse. He smirked. "Get on with it, now! We can review your wand work later."