What Episodes Is Towelie In What Song Does Towelie Play On The Guitar On The Professor Chaos Episode Of South Park?

What song does towelie play on the guitar on the professor chaos episode of south park? - what episodes is towelie in

The melody sounds like the dream of Aerosmith

Here is the URL of the video, the video clock is at 15:20
please help me understand

http://www.southparkstudios.com/episodes ...