This is a tough one. You have to click the mouse to give Santa air, and click the spacebar to drop presents into the chimney. While you are doing this, you need to avoid hitting birds in the air as they decrease your power. At the same time, you'll need to make contact with any food items in the air, as they give you more power. The farther you get, the better the surprise is when you eventually hit the ground. (You'll see what I mean!)
I've only made it 5.7 km so far. Can you beat that?