you keep me hangin' on

I should be embarrassed to admit that I've spent a considerable amount of time pondering this 7up advertisement from the September 1962 issue of Seventeen magazine.

Clearly, the girls are all in a dorm and they're waiting in line to use the communal telephone (thank goodness that by the time I hit college, each room had it's own phone!) Now three of them are apparently sipping on bottles of 7up and the tag line implies that if they just polish off those bottles that they'll not only suddenly be as "brightened" and "fresh" -- and well-groomed and well-dressed! -- as the girl who is currently hogging the phone.

My question is when does this transformation happen ........because the girl in the yellow sweater is next in line and it doesn't seem to be close to working for her yet. And where did the girl in the blue dress stash her empty 7up bottle? I don't even want to go there ......