Ride the flut flut was a mission that Jak and Daxter completed to obtain a power cell in The Precursor Legacy. Jak had to use the flut flut to cross the tar safely in Boggy Swamp, after Keira Hagai gained permission from the Birdwatcher and had it send over to the trans-pad.
One of the only two times where you get to control the flut flut, you'll find the bird deep in Boggy Swamp shortly after you break the third tether in Break the tethers to the zeppelin. Once in control of the bird, get on top of the nearby wooden platforms and from here make your way to tall ones standing over the tar-filled area. The power cell is over here on top of one of the platforms.