As someone else said, Happy Days was a nostalgic sitcom from the 70's set in the 50's...so the girls have no clue what Booster's doing. Just a weird guy who walked into the soda shop and hit the jukebox and then made a strange noise.
Huh...Happy Days was a sitcom that was supposed to be about the wholesome Cunningham family, but quickly got taken over by the Fonz...the cool bad-boy everybody knew and who just had to snap his fingers to have girls chasing after him. If this is one of the old tv shows Booster watched to learn 20th Century culture....that explains a lot....