"No. Um." Jack slowly starts to pick himself up, grabbing for his trousers when they do indeed threaten to slide off since the tails prevent them from hitting his waist. "Last night was... not a this-world-monster thing. I was like that where I come from, too. I just hoped it would not happen here because the moon is broken and can't be truly full. I am so sorry that I was wrong and didn't warn you."

This is not a very helpful explanation, and he knows it, but he's still reeling a little from the six tails. He'll fill things in, in a minute.