Aaron Freeman, co-founder of the seminally brilliant/annoying Pennsylvania rock duo Ween, announced to Rolling Stone yesterday that he's quitting the band, effectively bringing to a close one of the most improbable quarter-century-long runs in modern rock history. Ween were a joke band, but as joke bands went, they were "The Aristocrats," a joke that seemed like it would go on forever, branching off in strange directions, finding new ways to provoke and confuse and offend.