The Farmer flashing back to his happy childhood and sparing a tree he was about to cut down.
In the episode 'Two's Company', realizing that Shaun and Lola have fallen in love in each another as Lola was about to be taken home, Bitzer switches Lola in the truck with a decoy at the very last minute.
When the invitations are ruined before they can reach any guests, the disguised flock gives the farmer the birthday party of his dreams.
In the Christmas Episode, it's shown that the farmer would be celebrating alone, so the flock and Bitzer manage to completely decorate his living room and knit him a sweater out of their own wool for a Christmas present.
The farmer remembering who he is and saving Shaun from plunging into the ravine.