Okay, here's the deal.
I have been very close to a male friend of mine for five years, and I've had an on and off thing for him for three years.

And that's it. We're friends. And my feelings are completely on and off. But when they're on, they're very strong and all I can think about is him. And of course this is a week-by-week thing.

I want to kiss him like crazy.

I want to know how I can tell him how I feel without just coming out and saying it to his face and making everything awkward and screwing myself over.

Also, as of five months ago he's become a chick magnet so that's another problem.

What the hell do I do?

You need to invite him in for a kiss. Ask him out on dates. REAL dates. As in, just the two of you go out somewhere and have a good time. It can be something as small as a Starbucks lunch date or as big as dinner and a movie. Look into his eyes. Laugh at his dumb jokes. Touch him, either on purpose or "accidentally on purpose"

And during this time, you can judge whether or not you really like him. After all, it's only a date! He doesn't have to kiss you on the 1st or even the 5th. (Although if he has any interest, he'll be chomping at the reigns to do it.) Think to yourself, "Can I go out with him every week like this? Is he really what I'm imagining him to be?" The worst thing you can do is play with his mind by being interested one date and cold the next one.

So ask him out, if you're comfortable with that. The goal is to decide if you really want this guy or if you're attracted just because you can't have him.

Oh god you're a genius thank you.