Answer:
It sounded like piano music and it was coming from my living room, however, we didn't have a piano. I slowly got up to see what it was, then I saw a sight I never expected to see, not even in my wildest dreams: my dad was dancing in a very slow romantic dance with my mum and making out.
They were dancing to one of his old music collections, that was why I probably didn't recognize the sounds.
He had one hand on her waist and it slid further down, mum let off a gasp, they were obviously enjoying themselves, oblivious to the fact that I was just upstairs.
I turned around and went back to my room and with a smile shut my door.