Regular Show 3x33 "Diary"

Mordecai and Rigby go to Margaret's house to water her plants while she is gone for the weekend. However, Rigby doesn't want to do it and instead goofs off. Mordecai becomes angry at Rigby and shoves him, causing him to hit a bookshelf and break Margaret's diary open. The two attempt to fix it (which includes trying to put into a microwave which Mordecai refuses after what happened in It's Time), but only make things worse. Mordecai and Rigby take the book to Skips, who tells them that he can use a magic quill pen to transfer the words to another book and make it look identical to the real one. The three of them go to Margaret's house, where Skips instructs them to hold hands and keep their eyes shut while the quill pen transfers the diary's words. But Rigby becomes curious and opens his eyes. This interrupts the transfer, leaves it incomplete, and unleashes the guardian of Margaret's secrets. Skips tells them that she will kill them for looking at Margaret's secrets and the only way to stop her is to each reveal a secret of their own, which Mordecai and Rigby have trouble doing. After revealing their secrets, the guardian disappears, everything turns back to normal, and the three of them finish the transfer. Afterwards, when Margaret returns, Mordecai and Rigby realize that they never watered Margaret's plants. However, Margaret tells them that they didn't need to do so and that she actually instructed Eileen to do it. However, Eileen overheard Rigby's Secret, and went to work without her glasses on, to try to win Rigby over as she brings them coffee, but bumps into the table spilling it.

Note: In this episode it's revealed why Skips skips, why Rigby sleeps on a trampoline and what happened to his mattress, and that Rigby thinks Eileen looks hot without her glasses.