"Lovin' You" is an often covered R&B soul song from the 1970's. It was featured in the Season One episode, "Big Gay Al's Big Gay Boat Ride".
Background
Richard Stamos is hired to be the guest singer for the South Park Cows versus Middle Park Cowboys half-time show. Jimbo Kern and Ned Gerblansky plan to make him explode when he hits the high note of the song so they can win a bet on the outcome of the game.
Lyrics
First time:
Lovin' you
is easy cause you're beautiful
doo-n-doo-doo-doooo
Aaaaa (does not hit the high note), Lalalalala...
Second time:
Lovin' you
is easy cause you're beautiful
doo-n-doo-n-doo-dooo
Aaah (hit's the high note and exploding Enrique, the horse mascot.)