Rocky Horror Picture Show normalised a more sexually active lifestyle and breaking out of traditional values that society expects us to follow. Let's have a look at the song that allowed the peak of Janet Weiss' character arc.
"I've only ever kissed before'' confirmed what everyone in the castle was already thinking. Jannet was a virgin before Frank. "There was no use getting into heavy petting, it only leads to trouble" can be read two main ways. One is that Jannet didn't have a reason to have sex as through her religious upbringing telling her it only leads to trouble. This "trouble" in this context could indulge in the sin of lust or catching an STD. Or you could interpret it as Jannet not wanting to become pregnant especially with Frank N Furter's baby out of wedlock.
"I've tasted blood and I want more" is a reference to her going head first into her primal instincts to allow her sexual side to seep through. The line "Give yourself over to absolute pleasure" has come to the forefront of Jannet's mind almost like a devil on her shoulder yet she doesn't have the willpower to say no.
"I'll put up no resistance" is Jannet trying to grab a part of her innocence back playing the part of a petite undefended woman. We see Brad do this in Rose Tint My World asking help from his mommy. This reluctance would come full circle in superheroes as they both have to face society with their newfound identity.
The repeating line "creature of the night" at the end of the song is Jannet's sexual awakening as she wonders what it would be like to have sex with all these different people and enjoying the thought of lust taking over her life.

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Rocky Horror Picture Show theories (complete)
No FicciónI put most songs in the Rocky Horror Picture Show under the microscope for us to understand the intent of Richard O'Brien.