Howard wants Christmas Eve to only include the family, but Richie discovers that Fonzie will be all alone.

An alien, Mork from Ork, comes to earth looking for someone average, or humdrum, to study and picks Richie.

After being embarrassed at Arnold's by a couple of hoods, Richie wants to take a jujitsu class to learn how to defend and stand up for himself.

With Richie in a dating slump, Fonzie sets Richie and himself up on a double date with two of his girls, Laverne and Shirley.

Marion, tired of the monotony of everyday house chores, decides to enter a televised dance contest. When Howard won't participate with her, she secretly enlists the help of Fonzie. Arnold unwittingly tells Howard that Marion has been at Arnold's early in the morning with another man, and Howard becomes suspicious.

Joanie enlists Fonzie to be her partner for a marathon dance at Arnold's. She desperately wants to outlast cheerleading captain Jill Higgins who had cut Joanie from the squad earlier. Prior to the dance, however, Fonzie's motorcycle breaks down, and he is forced to push it for 12 miles.

After experiencing a few strange happenings, Richie begins to buy into the legend that the place where their Halloween party is to be held, the old Simpson house, is haunted.

Looking for work, Richie, Potsie, and Ralph agree to fix the fence of an attractive divorcee. When the woman leaves for awhile, Potsie and Ralph decide to take off, as well, leaving Richie to finish the job by himself.

Fonzie finds his his bike in pieces, and the search is on to find out who did it.

Joanie develops a crush on Potsie after he sings to her at Arnold's.

To allow Richie to have a night alone with his girl, Fonzie allows him to use his apartment and claim it as his own. Fonzie needs some rest, so he sleeps in Richie's bed without Howard, Marion, and Joanie knowing.

Thinking her life is dull and that she's always treated like a little kid, Joanie wants to join the Red Devils' gang.

Lori Beth reports that Richie isn't moving after they crash his new motorcycle.

An ill Richie is home alone after the rest of the family go to see Cinerama. When he goes to see what is causing noises downstairs, he finds a burglar.

To hide from overzealous fans, a popular rock group (one of the members was Richie's childhood friend) is staying at the Cunningham house, but Richie can't tell anyone that they're there. This poses a problem for Richie because nobody believes he actually knows them.

Needing to make a good impression for a prospective business deal, Howard asks Richie to take the ""Prince of Porcelain's"" daughter out on a date. Richie, however, already has big plans and asks Potsie to take his place and pretend to be him.

With nothing to do for the Easter holiday, Richie, Potsie, and Ralph decide to rent a cabin at Lake Whitefish. They pretend to be adult businessmen in order to secure the cabin and get girls.

After having been in several fights recently, on the advice of the Cunninghams, Fonzie agrees to see a psychologist.

Potsie saves Fonzie from a fire at the garage. Out of gratitude, Fonzie grants Potsie any one favor, and Potsie wants to pal around with the Fonz.

Richie makes a lucky shot to win a basketball game and suddenly becomes a big hero.

Richie and Potsie are invited to Potsie's cousin's stag party. In an attempt to lessen the effects of the alcohol they will consume, they each drink several cartons of milk and a sip of olive oil.

Howard's old army buddy, a black man, asks Howard to be the best man at his wedding. Howard and Marion consider holding the wedding at their home when the man can't find anyone else willing to do it.

Richie buys a car from Fonzie and finds out that it is stolen.

Richie wins a date with a movie star, Cindy Shea, to a school dance, and Gloria breaks up with him because of circumstances surrounding it. Cindy, however, will only be able to meet up with Richie after the dance has started.

Richie and Potsie plan to host a poker night at the Cunningham house as Howard and Marion will be out of town. However, their plans change when three young women stop by after their car breaks down, and Potsie invites them to stay the night.