What would be the premise of the strip if the radio was not turned on?

Anybody’s guess…she could be trying to sneak away from the top apartment for unknown reasons and hastily decide to abort when she notices his little-too-happy gaze when he sees her in the window, accidentally knocking over the radio in her hurry.

Given that a theme in these is usually involving unwanted male attention and her escaping it in various ways, that IMO makes more sense given the available information in this strip.