The song from Chapter 16 by itself.

Icon created by  TKDye. Full image can be found here

Backing track was done by the incredible  kobi-lacroix . Original song written and performed by The Beatles.

So, after the reception that Surf She Bear got, Birch decided that if Dipper was going to do any more songs, he was going to need some vocal training. So, he hired someone to give Dipper lessons, two hours a day, for two weeks.

Then back into the recording studio he went, and recorded this. When Birch emerged from the mixing room, after listening to the final mix, he had tears in his eyes, and gave Dipper a huge hug.

Oddly, Dipper didn't mind.