The episode starts as SpongeBob and Patrick walking to each other and then they start to play - the idea of their game is to holler at the vehicles that pass by, which angers Squidward and some of the people in the vehicles. Then, Patrick falls asleep and when he wakes up he has a beard. Then, Squidward passes by and offers to teach Patrick everything he knows about how to be mature which upsets SpongeBob. SpongeBob decides to follow them promising he will learn how to be mature as well.
The three go into Squidward's house for a grown-up makeover. SpongeBob shows off his new look. Patrick likes his look until Squidward reminds him that he really shouldn't.
They then go to a restaurant, and Patrick and Squidward order some tetrazzini while SpongeBob orders the milk and cookies.
Then, they go to the art place and SpongeBob follows them around and Patrick and Squidward tell the security to kick him out and he first put him out softly, but he doesn't leave so he ends up kicking him. SpongeBob sees Squidward and Patrick walking and Squidward mentions that the beard was the best thing that ever happened to Patrick other than himself. SpongeBob tries to remove his beard to restore his friendship. Squidward stops him and says that they are through with him.
Then, Squidward and Patrick go to the Opera House and they see a lady which is really SpongeBob singing opera which Patrick says "she's beautiful."
After SpongeBob sang opera to win Patrick back, Patrick begins to cry and sees the beard is really a sea urchin and the sea urchin woke up and ran away from Patrick. He chased it until SpongeBob says Patrick's name and he says "How do you know my name?" and he says that he is SpongeBob and they make up again then Squidward told all the guests that the show is horrible, but they disagree and threw food at him then the episode ends.
In this episode, Squidward says that adults should never play with children, give each other high fives or have fun, which is not exactly true. This could just be just an example of Squidward's snobbish ways and his own views of maturity.
Squidward said something similar to this in the episode "Snowball Effect" when he was debating with SpongeBob and Patrick on whether if snowball fights are for children or adults.
This is one of few episodes with Squidward's full first name on the title card instead of "Squid."
Note that when Squidward and Patrick were walking toward the Opera House Squidward changes clothing, from just a simple red bowtie and his regular brown shirt to a full on formal shirt, vest, purple bowtie, and jacket, it is possible that before that scene that Squidward went back to his house to change.
It should also be noted that the suit Squidward was wearing is the same one Squilliam was wearing in "Professor Squidward" and "I ♥ Dancing."
This is the second time Patrick uses a lot of big words for nearly the entire episode. The first was in "Patrick SmartPants."
Running Gags: Squidward mumbling to himself, and SpongeBob and Patrick Boat Screaming by different vehicles.
In "Home Sweet Rubble," in Patrick's Dream office, two of his pictures from this episode can be seen on the walls.
The paper that SpongeBob originally took out while on stage had the infamous "There once was a man from Nantucket," limerick, which is known for being very risqué.
The sea urchin was much like a bush, and no one was afraid of it, unlike the urchins in "Eek, an Urchin!"
Larry's S.U.B. truck from "Drive Thru" makes a small reappearance in this episode.
When SpongeBob smudged the painting, he blurred the "mildly nude" parts. The painting was also a parody of a famous painting called The Birth of Venus, but with fish instead of people.
The plot of this episode is very similar to the My Gym Partner's a Monkey episode. "Nice Mustache," since both involve a main character gaining facial hair, causing them to change their behavior, only for the facial hair to turn out to be a fuzzy animal by the end of the episode.
How the sea urchin didn't wake up before Patrick started crying is unknown.
When Squidward and Patrick were walking to the concert, Squidward was wearing his brown shirt and a bow tie, but when the scene changed, Squidward was wearing a tuxedo.
They could've gone back home and changed which would also explain why Patrick was wearing a top hat and had his cane when the scene changed, he didn't in the previous scene.