One of the times that Mason woke up last night, he woke up Adam. Thankfully, Adam usually sleeps thru everything. But, when I went into their room to check on Mason, Adam was standing up in his crib, singing "Naptime, naptime, time for sleep, time for sleep," a song that he learned from those weird characters on Yo Gabba Gabba.
He eventually laid back down, pillow over his head, still singing.