Arnold's (Arnold's Drive-In) is the local restaurant where most of the cast usually hangs out.
The company was originally called Arthur's Drive-In, but in later years, it was changed to Arnold's Drive-In.
The jingle goes: "Come to Arnold's Drive-In for real good food and music".
The bathrooms are labelled "GUYS" and "DOLLS".
It has a large "A" in yellow on the roof, and inside it features a jukebox and several flags. Ever since Marion Cunningham dissed their food in Marion Rebels and called it "unhealthy" and "garbage", they have had a rule never to say the word "garbage" in front of the customers, even when not referring to the food, as it is a gross word and may make them lose their appetites.
Richie calls it a "hangout".
The men's toilet is where Richie Cunningham, Warren "Potsie" Weber, Ralph Malph, and occasionally other men go to ask Fonzie, for advice, and Fonzie calls it his "office". Also in the bathrooms, the guys, including the chefs, read the graffiti on the walls, and apparently there is lots of graffiti about the Fonz in the women's bathroom. Arnold himself even wrote something on the wall in Three on a Porch. Fonzie writes advice on the bathroom wall too.
Fonzie has a rule against robbing Arnold's.
The jukebox there is very popular, and Fonzie can make it play by hitting it, but when Richie and Potsie tried, it didn't work.
In A Mind of His Own, Fonzie made a birdhouse of it.