There are many times when I worry that my parents would flip if they knew the real me.
Could you explain this further? Why do you think your parents don't know the real you?
Because they think I'm a very loyal and responsible guy
I can understand why you would not want to open up to your parents, it's not an easy thing to do.  If you are honest about who you are, however, they will respect you more and life could be much easier for you.
Maybe, I might tell them some day.
It's good to finally open up to your parents, and I think you would feel great afterwards. Lying to anyone, especially loved ones, will always make you feel guilty and bad.