This is an odd little sketch. It's cute, and it's always fun to watch Henson & Oz play off each other, but I'm not convinced the payoff is totally worth it. Maybe it would have been funnier with either Bert or Cookie Monster: Bert would get humorously exasperated with Ernie for making a mess, and Cookie Monster would try to eat the items before Ernie put them in the box. On the other hand, of the three of them, only Grover could have delivered the punchline as written; Bert would never climb into the box, and Cookie Monster wouldn't mind the mess.
Frank Oz originated three main characters on Sesame Street--Bert, Cookie Monster and Grover--and I realized recently that the three of them form a Freudian trio. It's not readily apparent because the three of them, for obvious reasons, don't appear together in sketches very often. Nevertheless, Cookie Monster, with his insatible appetite and primal speech patterns, is the id; Bert, with his cautious and orderly ways and fear of looking silly, is the superego; and then Grover, who desires nothing more out of life than to please others, is the ego.
As I continue to think about it, if you count Kermit, then Jim Henson also played three significant characters on Sesame Street--Kermit, Ernie and Guy Smiley--who also form a Freudian trio: Guy Smiley, the excitable game show host with no indoor voice (unless he's singing), is the id; Kermit, who on Sesame Street usually either gives lectures or serves as the roving reporter for Sesame Street News, is the superego (as he was on The Muppet Show as well); and fun-loving, easygoing Ernie is the ego. So that's why I think Ernie and Grover don't appear together in sketches very often; they both represent the moderate ego character type. Ernie is so easygoing and Grover is so adaptable that they don't create good friction together.
Bert & Ernie are usually a pair, of course, and other common pairings among these characters are Ernie & Cookie Monster, Kermit & Grover, and Kermit & Cookie Monster; both Cookie Monster and Grover have appeared on Guy Smiley's game shows, but to my knowledge there's never been a sketch featuring Bert & Kermit or Bert & Guy Smiley. We've probably never seen Bert & Kermit for the same reason we rarely see Grover & Ernie, and Bert would probably think game shows are too silly for him.
By the way, I don't know if all this Freudian subtext is deliberate or even intended, but I will say that it appears that Jim Henson had a lot of fun playing with Freudian imagery in a particular Muppet Show sketch, in which the female creature has a phallic-looking nose, etc.
Speaking of the letter N reminds me of this song:
This song appears on the "Old School Vol. 3" DVD set, and it only evoked vague childhood memories for me, but the moment I heard it on the DVD, I said to myself, "That sounds like the 'Capital I' song!" I did some research and sure enough, they were both written and performed by the same person.
I want to post another video of Grover being adorable, which is all of them, but here's a nice one that's short and sweet:
And because I mentioned Sesame Street News Flash, here's one of the most memorable examples: