All I can remember is this one scene.

Xander is a fledgeling and is riding on the back of Spike's motorcycle. He was shouting directions into Spike's ear. Eventually, Spike let him drive, only to shout directions in his ear. Xander almost crashed the bike because it was so loud. Then Spike drove again, and Xander was much quieter.

Hopefully, someone knows what fic this is. Thanks!