Season 4

01 Full Moon Episode 110th March 1999 Harold, Sid, and Stinky all moon Principal Wartz, but Arnold is blamed, even though he was just an innocent bystander. 02 Student Teacher Episode 210th March 1999 Helga's sister Olga comes home for spring break and becomes a classroom aid in Helga's class, much to Helga's chagrin. 03 Big Gino Episode 315th March 1999 After Sid works off a debt with loan shark Big Gino, the two become friends, but when Sid is told to give Arnold a swirlie, he has to choose between the two. 04 Jamie O in Love Episode 415th March 1999 Gerald's older brother Jamie O has a sudden burst of kindness when he finds a girlfriend, but Arnold and Gerald soon find out that the girl is just using Jamie O. 05 Eugene's Birthday Episode 517th March 1999 After losing Eugene's birthday party invitations, Arnold feels obliged to throw him another party, but it doesn't work out. 06 Stinky's Pumpkin Episode 617th March 1999 Stinky grows a huge pumpkin to enter in a city competition. 07 The Beeper Queen Episode 729th March 1999 After Bob pops his spine, Miriam runs Big Bob's Beepers. She gets in over her head and forgets about her family. 08 Oskar Can't Read? Episode 829th March 1999 Arnold finds out that Oskar is illiterate and tries to teach him to read. 09 Dinner for Four Episode 931st March 1999 Helga wants to show Arnold that she can be as sophisticated as Lila is by taking him, Gerald, and Phoebe out to dinner with a coupon she won. She devises a plan to get out of paying when she discovers they're at the wrong restaurant. 10 Phoebe Skips Episode 1031st March 1999 Phoebe is promoted to the sixth grade, but realizes that her new so-called "friends" are just using her to do their homework. 11 Helga's Parrot Episode 115th April 1999 A sleep-talking Helga confides into Bob's parrot about her love for Arnold. The next day, the parrot flies into Arnold's window, and it is up to Helga to get it. 12 Chocolate Turtles Episode 125th April 1999 Crisis strikes when Gerald's little sister, Timberly, eats a stock of chocolate turtles that he and Arnold are supposed to sell for a local scout organization. 13 Love and Cheese Episode 137th April 1999 Helga tries to separate Arnold from Lila while at the annual Cheese Fair. 14 Weighing Harold Episode 147th April 1999 Harold, after discovering his friends think he is obese, decides to go on a weight-loss cruise. When he comes back, though, he is noticeably larger. 15 Back to School Episode 1511th September 1999 After Grandpa tells Arnold that he never got his grade school diploma, Arnold convinces him to come to go back to school at P.S. 118. 16 Egg Story Episode 1611th September 1999 Arnold and Helga must care for an egg for a school project about parenting. Meanwhile, Rhonda and Harold are project partners and must also take care of an egg. 17 It Girl Episode 1718th September 1999 Helga becomes a model, but she quits after she gets irritated at everyone dressing like her. 18 Deconstructing Arnold Episode 1818th September 1999 Arnold's classmates are tired of constantly telling them the right thing to do, so he stops giving them advice. Nevertheless, when his classmates get into sticky situations, they are in desperate need of his advice. 19 Grudge Match Episode 1925th September 1999 After getting in a car accident, Bob and Grandpa face off on the golf green, with the loser having to pay for the damage to both cars. 20 Polishing Rhonda Episode 2025th September 1999 Rhonda attends a finishing school, but is far from impressive with her stroppy attitude, and seeks help from fellow student Big Patty. 21 Weird Cousin Episode 219th October 1999 Arnold's bland country cousin, Arnie, comes to visit. Arnold begins to notice that Arnie and Lila show interest in each other, making him jealous. 22 Baby Oskar Episode 229th October 1999 Oskar has to take care of his infant cousin-in-law (also named Oskar), while both Susie and her cousin are gone. 23 Grandpa's Sister Episode 2316th October 1999 Phil's twin sister comes for a visit, bringing along an unsettled conflict between them. 24 Synchronized Swimming Episode 2416th October 1999 Arnold and the gang are part of a synchronized swimming team led by Coach Wittenburg. 25 Helga Sleepwalks Episode 2523rd October 1999 After eating pork rinds, Helga sleepwalks, uttering her secret about Arnold as she does so. 26 Fighting Families Episode 2623rd October 1999 Arnold, Grandpa, Grandma, Ernie, and Mr. Hyunh compete on a game show against a "perfect" family from PS 119 27 Headless Cabbie Episode 2730th October 1999 Arnold tells an urban legend about a decapitated taxi driver. The gang goes out, only to find the details in the story are becoming real. 28 Friday the 13th Episode 2830th October 1999 Arnold and Gerald try to prove superstitions are fictitious, only for it all to backfire on them. 29 Veterans Day Episode 296th November 1999 Arnold's Grandpa recalls his adventures as a soldier in the Second World War, outwitting a regiment of Nazis, while Gerald's dad, Martin, remembers his own time serving in Vietnam. 30 Helga on the Couch Episode 304th December 1999 Helga confides in the school psychiatrist about her social life, family life, and her love for Arnold. 31 Dino Checks Out Episode 3111th December 1999 Dino Spumoni is found missing and then declared dead after what appears to be a suicide attempt. but Arnold finds out that this isn't the case, and he secretly lives in the boarding house, believing that his work will skyrocket in value after his "death".