Weezer.com has posted news that one of the most unlikely reunions has taken place - Weezer frontman Rivers Cuomo recently joined estranged original bassist Matt Sharp during the latter's acoustic performance at Cal State Fullerton. The duo played an old, pre-Weezer song, a new collaboration they had written, and "Say It Ain't So," following it up with an unexpected encore of "Undone - The Sweater Song." Weezer.com states that "the two have gotten back in touch as friends and are now keeping in touch and sharing music, separately from their individual works in Weezer and Matt Sharp solo." No word on if this will remain a one-time thing or blossom into something new entirely.