What does this dream mean?

I was at a museum with my friends and we each had to do speeches inside and I didn't write mine so I just used one of my friends but I was looking for someone or something, and peered inside a little telescope or microscope and saw a bloody string with a bloody knife and a head hanging there with my friend talking there. I just shrugged and started looking somewhere else. I peered in whatever it was again and it was the same thing and voice there then I realized that the head was me. I got really scared but still looking for something. And then I just woke up.