A dangerous parcel?

I was getting for work when the bell rang. It was the postman bringing me a very peculiar parcel. I made a signature in a paper and he left my home. I stayed three or four minutes looking at it, I wasn’t waiting for any box, and I didn’t know what it could be.
I took a look at the clock, I was late! Iput the package on my night table and I went running to work.

The days, was being normal, as any day I’ve lived. And I didn’t think anymore in the parcel.

At half past nine I arrived home. I still didn’t remember the box and I went, as any day, to have a shower.
When I got out of the shower everything was normal, I put my pyjamas and I went to have something for dinner.
Later, when I had already had dinner, I sat on the sofa to watch the television. But in a quarter hour I fell asleep.
I got up in a half our, or this was what I thought, I had a look at the clock and I had a surprise, it was half pas two at the morning! I went to my bedroom to sleep in my bed but when I came in, I saw something brilliant in my night table. I had a big surprise, my heart started to beat hard, and then, searching in my mind, I remembered the postman and the parcel. I calmed down, but there was something suspicious in the parcel. I went cautiously and slowly to my night table. My heart started to beat hard another time, I picked the box with my hands and I started to open it cautiously.
When it was opened a calmed music started to sound, and I started to laugh; it was a song box!