Variation on a Sippy Cup

When I first introduced the sippy cup to Martin, I didn't think that he would ever figure out how it worked. Now he is an old pro, apparently so much so that he is bored with normal sippy cup use and has developed a new method of drinking from one. Some of his sippy cups have soft tops with built in valves like the one shown.

For the last few days he has been drinking while holding the cup in the wrong direction. (So the spout is higher than the valve) He thinks it is fun to have to tilt his head really far back to drink. Today while he was drinking this way he somehow discovered that if he put his mouth over the valve and sucked, he could get the juice out too. It looked so funny; I tried to get a picture, but the second I got the camera out he stopped. This is the only picture I got. I think it is cute, so I will share it, even though it doesn't show anything pertaining to my story.
And yeah, he has a fat lip...he fell and hit his face on one of his toys.