Hey Arnold!: Season 1, Episode 15
Olga Comes Home/Sally's Comet (25 Nov. 1996)
When Helga's older sister, Olga, comes home from college and gets all of her parents' attention, Helga plots to sabotage her sister's visit.Arnold and Gerald save up cereal box tops to get a telescope before the arrival of Salley's Comet.
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