Second part of last weeks comic, where Dad awoke to find Baby standing in her crib. So, here he lowers the crib and baby wonders why she is lower than normal. 
This happened with me and my daughter.  I Had to lower the playpen and her crib. Also, had to basically baby proof the rest of the house because she had learned that she could climb up and stand to a lot of places and crawl around to get to them.