Fold in half diagonally.
Fold one edge towards the hypotenuse crease.
Do the same for the other side. (I unfolded the original crease)
Fold the corner (in the upper right in the previous picture) back and behind.
Crease again along the original diagonal fold from step 1.
Fold the bottom edge up to meet the upper edge.
Fold it back down but at a slightly different angle. This is a "flipper".
Do the same on the other side.
Fold the top out to form a head-looking thing.
Form the beak.
Fold the bottom edges up a bit, if you want. This will make it easier for him to stand. Or her.
Now you can flatten out the stomach a bit.
Formal attire optional.