How to come out to the parents?

[Percy]

Tell them. Like, sit them down and tell them. They'll probably tell you that they already knew, and you'll all have a big laugh, and then you can all go and have ice cream. Maybe you can invite your girlfriend.

There's not really a "how". The only requirement is saying the two little words, "I'm gay." Once you've done that, everything else will proceed naturally. Probably the best way is to just wait until after dinner one night, or some other time that you're with them, and then say, "Hey, I wanted to tell you guys something - I'm gay. I started thinking I might be when I was 13 or 14, and I've been sure for a while now. XXX and I are dating. I just wanted to be honest with you." You don't need to make a big speech - they'll generally have a lot of questions for you anyway. Just answer them as truthfully as you can, and listen respectfully to anything they might say.

You'll be scared and shaking in your boots, but you've got to bite the bullet and just do it. It's like skydiving - everyone's scared in the plane, but once they're on the ground, they've got big smiles on their faces. The nice part is, like I said, the only hard part is saying, "I'm gay." Once you've done that, everything else will be easy. Don't beat around the bush, just say it and let whatever will happen happen.