I am looking for a Spike/Xander fic - I think that it was set following the episode School Hard. I remember Spike buying Xander clothes that fit better. After that they went to a demon restaurant that served Dim Sum. The restaurant didn't usually let humans in and Spike made Xander go up and try to get them a table. Xander's attempt made the demon (bouncer?) laugh so hard that he let them in.