Happy Days: Five things you didn't know We reveal five things you (probably) didn't know about 1950s-set sitcom Happy Days, which is injecting some cool into weekdays on Gold (10am and 2pm)... of 5 Popularity contest Think of Happy Days and you think of The Fonz, right? But, believe it or not, Arthur "Fonzie" Fonzareli started out as a minor character and actor Henry Winkler was originally fifth-billed on the show. However, his growing popularity with viewers saw him steadily rise through the ranks until he got star billing in the sixth series. Rumour has it that the network wanted to rename the show Fonzie's Happy Days at one point but backed down when some of the other stars threatened to quit. Watch Happy Days on Gold. Weekdays at 10am and 2pm Star cameo A pre-Hollywood Tom Hanks showed off his martial arts skills during a 1982 appearance on the show. Hanks played Dwayne Twitchell, an old schoolfriend of The Fonz, who challenges the coolest guy in Milwaukee to hang up his leather jacket for a spot of fisticuffs in the diner. When Fonzie refuses, Dwayne promptly chops up the furniture in a performance that hints at future Oscar success. Fact fans may also be interested to know that Ron Howard, who played Richie Cunningham for the first six years of Happy Days, went on to direct Tom Hanks in hit movies including Splash!, The 'Burbs and Apollo 13. Watch Happy Days on Gold. Weekdays at 10am and 2pm Missing in action Ever suffered from 'Chuck Cunningham Syndrome'? We're hoping not as the term (inspired by Happy Days) refers to a character in a TV series disappearing suddenly without any explanation. In the case of poor old Chuck, he made fleeting appearances during the early days with actors Gavan O'Herlihy (pictured back, centre) and Randolph Roberts portraying him in series one and two before being dropped altogether without another mention. In fact, Howard later talks about how proud he is of his "two kids? in a cruel twist that sees Chuck written out of TV history entirely. Whatever did he do? Watch Happy Days on Gold. Weekdays at 10am and 2pm Beware of the shark In the fifth series of Happy Days, which was originally shown back in 1977, The Fonz did something that would change the course of TV history. He jumped the shark. The episode in question featured the show's most bizarre storyline to date when a water-skiing Fonzie (wearing denim swimming trunks naturally) jumped over a shark while being cheered on by his friends. The term 'jumping the shark' has since entered popular culture to describe the moment when a TV series introduces an outrageous plot in a bid to boost ratings. See most TV shows that have been running for more than a couple of series. Watch Happy Days on Gold. Weekdays at 10am and 2pm The Happy family Happy Days spawned a mind-boggling seven spin-off series - the most successful of which was Laverne & Shirley, which ran for an impressive eight series. Another spin-off that was also a hit with UK viewers was the Robin Williams-starring Mork & Mindy. Yes, Mork the alien made his TV debut on Happy Days in yet another 'jumping the shark' moment. Lesser successful tie-in series included Joanie Loves Chachi, Blansky's Beauties and Out Of The Blue. Watch Happy Days on Gold. Weekdays at 10am and 2pm Slideshow Pause Show Images Hide Images Tweet