This whole song is basically just the same chord progression repeated over and over again.
***
I just had sex
And it felt so good
***
Then you take it up a half-step for the key change at the very end.
I just had sex
And it felt so good
***
If you'd prefer to play the whole song with a capo on the first fret, try this:
Capo I
I just had sex
And it felt so good
***
Then the key change at the end with a capo on the first fret would be:
Capo I
I just had sex
And it felt so good