The Fishermen Lullaby is a song Flapjack sings in the episode "Jar She Blows!"
Lyrics
Go to sleep little fishermen
And I'll grant you your wishes then.
Go to sleep and I promise you
Your wishes will come true.
For tomorrow's another day
For you to laugh
For you to play,
And tomorrow you'll wake and see
A wish granted to thee
(whispers) By me...