You'll gain control as a drunk Conker. You can't jump or walk fast, but during this level, you won't take any damage.
First, go to the scarecrow, the entrance is on the other side of the island around the fencing. The scarecrow will introduce himself as Birdy, and explain the function of B-buttons. Walk onto the B-button on the floor and press 
for the first context sensitive event.
Then Birdy will open a gate to another B-button, walk to that button and press – you can guess it – . You'll drink some milk and the hangover will pass - and receive an instruction on how to skip cutscenes (but only if you seen them before or are using the chapter unlock cheat.) You should now be able to swim to the small island on the other side of the river without being pushed back. After a short cutscene, you will be shown the controls to jump, helicopter-jump and crouch.
As you cross the platforms using the helicopter-jump. Notice the door. To open it, climb to the top of the cliff and jump to the handle to pull it down and open the door. When you enter the door, it closes behind you. From here, you will learn the new move that allows you to swing a frying pan. Use it to knock down the key and pick it up to unlock the door.
Climb to the top again speak with the gargoyle. After the cutscene, swing the frying pan. The gargoyle no longer blocks the path, but his fall causes a boulder to block the exit. Jump on the rock, and helicopter to another B-button. Press . You'll have some TNT and you can blow up the rock. Go through the entrance and you can go to the "Windy" stage!