Of course Sirius was still joking. It was sort of his defense mechanism, his way of showing that they couldn't get him down. Also helped keep his moral up, which wasn't easy given how much pain he was in and knowing that it wasn't likely to end any time soon.

He tensed at Severus's hand as if expecting to get hit, then only slowly relaxed again, to make it seem as if he hadn't been worried.

"Don't know, I don't have a watch. Few days, I'd say."