WXPN is a radio station of the University of Pennsylvania. This statement is a bit ambiguous; they're not a "college radio station", in that they're not student-run, but rather a professionally-run, public (i. e. non-commercial, and every so often they come on the air and beg for money) radio station. WQHS is the student radio station. I've been working from home this week, since it's our Spring Break, so I've been listening a lot.
Every weekday morning at nine they have a "select-a-set": listeners call or e-mail and suggest three songs, which are perhaps somehow related. Somebody suggested the following three songs today, which got played:
Sarah McLachlan, Circle
Edie Brickell & New Bohemians, Circle
Joni Mitchell, Circle Games
Why? (Hint: the select-a-set feature does not exist on Saturdays.)