What's in the bag!?

So, one summers evening I was driving down a small rural road and I come across a hitch hiker. Being the nice guy I am I pull over and let him in, he placed his large black duffle bag in the back and jumped into the front seat. We are driving along the road, which I might add is quite bumpy, every time we hit a bump his bag in the back seat would make some weird noises. Being curious, I asked him what he had in the bag to which he replied "It is not really important or any of your business"; so I just minded my business and shrugged it off. We keep going down this road and the bag continues with the strange noises, so once again curiosity overtook me and I asked about the bag again. This time he seemed even more fed up with me and said "Listen, if you needed to know about the bag you would, it's none of your business, so just keep driving." So at this point I start to become impatient and it wasn't five minutes down the road when we crossed an old bridge and with this the noise that came from the bag was louder than ever. So, I pulled over, looked at the hitchhiker and told him that he is either going to tell me what's in the bag or get out, to which he replies "What's in my bag is none of your Damn business!" so I kicked him out and continued driving. I then realized that the bag was still sitting there in the back seat so, I turned around and unzipped the bag.