I'm not surprised. South Park is famous for mocking just about everything that's out there.
I remember one episode where they mocked Barbara Streisand by pointing out that her weakness was her nose.
South Park Episode Player
(In real life, Barbara Streisand prefers to be publicly viewed from the left. That's why Rosie O'Donnell reversed the arrangement for her show when Barbara Streisand appeared.)
YouTube - Barbra Streisand TV interview