Happy Days: the words themselves bring back an intense flashback of childhood.
I used to watch Happy Days when I was a kid, in the 70s. At first I watched it on a black and white TV, and then my family got color.
Happy Days was a main force in shaping my idea of the USA (only at that time I wasn't refined enough to call it "USA", I just called it America and that was more than enough). The country was clearly a happy country. People dressed in bright colors and hung out at Arnold's.
Teenagers drove cars, big cars with crome. In Italy we didn't have Arnold's, and our cars were dinky FIATs.

But what is more, Happy Days contained Fonzie, and Fonzie was the definition of cool. Black leather jacket. Stiff haircut. And the women, the women just went insane for Fonzie. It did not matter that the US were not like Happy Days any more, and that I was not living there, and that it is doubtful if the US ever where like Happy Days. Realism was not very interesting.
At that time, I hoped that eventually I would grow up to be like Fonzie. It was a terrible shock when I saw a picture of Fonzie/Henry Winkler in 1985 as he was then: a rather chubby 40 years old guy.

An IMDB search on his movie career is even more depressing. How could he be so damn cool back then, and then turn into this presence that clearly haunts B-movies and flops? Or, conversely, how could we think that he was so cool back then?

Still ... every time I give someone a thumbs-up, it is the fonz that moves my thumb.