Where did he learn this?!

How on earth did he figure out how to stick his tiny little toes into those holes and climb straight up the gate? I was washing some dishes and went to check on him and I saw him climbing up! I happened to have the camera nearby and I snapped a picture before telling him to get down. Wouldn't you know the little stinker climbed right back up it? He got up further the second time to where his belly was at the top and he was leaning over. I freaked out that time and didn't take a picture. I yelled "NO!" very loudly and he got down and looked at me and said "oh". Like he knew he was in trouble! The little stinker!