The entire "Fairy Tale" episode is a riot, but the best part has to be at the end, with the Fourth Wall logic that Princess Gwen (played by Michael Nesmith) uses to turn down Peter's marriage proposal.
In "Monkees ŗ la Carte," the band disguise themselves as the Purple Flower Gang, but goof by wearing white carnations. Micky waves it off by saying, "You know how tough it is to find purple flowers, Baby?" When Peter goes to the police, they immediately grab him as a member of the Purple Flower Gang, and they respond to his pointing to his white flower with "Don't give me that, I know how tough it is to find purple flowers!"
In ďThe Monkees Paw,Ē standing by the wooden Indian statue.
Davy (likely VERY stoned, leaning against the Indian): You know, he (Micky) hasnít said a thing in 12 hours?
Mike: Thatís it! In 12 hours, he forgot how to talk. I mean anybody can forget how to talk in 12 hours!
Peter: Well, then itís simple. All we do is teach him to talk.
Davy: (raises hand) How?!
Mike: WHAT did you sayÖ?
Peter's interview with a very literal computer goes horribly wrong in "Monkee Vs. Machine". Funny in and of itself, but then Mike goes for the same interview and brilliantly uses the computer's logic to short circuit it. Have a look here and here.