Actually, he probably should have checked in with Buffy first, to let her know about the freaky fireworks or with Willow for commiseration and maybe some clothes that fit. But he went with the old standby: "Freaky things" equals "Call Giles".
So he stood at Giles' doorstep, his pants drawn tight and the legs rolled up. Giles must have heard the first, very tentative knock, so he surprised Xander while he was still rehearsing his speech.
"Hi Giles, it's me Xander, I'm just back from my road-trip and there was this fire on Restfield, and I'm not supposed to be home anyway yet, so I had time and I went and wanted to check it out for Buffy and there were these demons and they were chanting and I thought chanting was of the bad and I got me some rocks and thought I could maybe get them out of the rhythm because, well rituals are pretty exact I thought and maybe I could abort them and I started throwing and they stopped and there was a freaky firework and I passed out and when I woke up, the demons were all sludgy and I'm a girl and I really can't go home that way and can you help?"
Giles frowned and examined the girl in front of him. Xander fidgeted and hitched up his pants which were sliding in defiance of the towline he had tied them with.
After a moment of uncomfortable silence, Giles sighed pinched his forehead and stepped aside in a silent invitation.
Xander let out a breath he hadn't been aware he was holding, and stepped inside.
"Oh thank god. I'm really glad you believe me."
"Xander, there are two things I have learned here in Sunnydale. One, never discount the impossible, it happens more often than you know and two, long, run-on sentences with utter disregard for grammar, idioms and breathing, are pretty much an identifying characteristic for Buffy, Willow and you. Besides, I can easily recognise your panicked expression. I do have some experience with it."