Clip from Grease:
It is representing a typical teenage boys mindset/what they think is 'cool', in comparison to how girls would want a relationship to be about. It is being represented by portraying boys as being mainly concerned with sex and not the actual relationship, whereas it is illustrating how girls can be quite naive when it comes to relationships. You feel quite sorry for Sandy by the end of this as it seems like she genuinely liked Danny in comparison to him maybe using her. These teenagers seem quite normal and this makes it more realistic, in addition it explains the stereotypical thought processes of girls and boys.