With Discovery's "Shark Week" and NatGeo Wild's "SharkFest" both beginning July 5, we thought we'd clue you in to five things you might want to know about one of TV's most-fintastic moments: the "Happy Days" episode that spawned the phrase "jump the shark" (or when a show began going downhill):

1. The episode, which was part of a three-episode arc set in Hollywood, aired on Sept. 20, 1977.

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2. It ranked No. 3 for the week and garnered a 50-plus share (which would be unheard of today), an audience of more than 30 million viewers.

3. The phrase "jump the shark" was inspired by a scene in which Fonzie (Henry Winkler) water-skied over a shark.

4. In real life Winkler was an avid water-skier. (He had actually been an instructor.) His father suggested that his son's skills be used in a "Happy Days" episode.

5. "Happy Days" really didn't jump the shark after this episode aired. The show remained on the air for six more seasons (164 more episodes) and ranked in the Nielsen top 25 for five of those six seasons.