Even though I really like this song... I never really got the episode that much ;-;

You Gotta Do What You Gotta Do is in Season 12 episode "Elementary School Musical". This episode is a parody of High School Musical. 

 It is a cool song if I do say so myself. The only problem that I have with it is that it's hard for me to tell who's singing between Stan and Kyle (STYYYYYLLLLLEEEE). But I really like the part where Cartman hits a high note! That jawn was boss. 

Oh and for those who are wondering what Kenny says that is muffled, it's "If you wanna get high and jack off, it's cool!" 

So here it is, You Gotta Do What You Gotta Do by: Stan Marsh, Eric Cartman, Kyle Browolski or some shit, and Kenny McCormick

https://youtu.be/Hg22rT6prHI