The file
The hopscotch chant at the start is the part everyone does, and it isn't in the song; it's Penny Marshall and Cindy Williams skipping down a Milwaukee street. Then Cyndi Grecco's theme kicks in.
Gimbel and Fox wrote it as a companion to Happy Days and it charted too. The Shotz brewery, the L on the sweater, and the chant.
Sources: Wikipedia — Laverne & Shirley