I've been in a similar position. I was 18 and met with a guy who took pictures of me, fully nude, face and all, and fully erect. I am now in my early 30s, and I cringe when I think of those photos. I wasn't doing anything sexual per se, aside from standing there with a boner, but I just don't like the position I was in then. I was naive and dumb. I later learned that this particular photographer targeted young males, known in the gay male photography genre as "twinks." So, I guess I was an unaware twink.
The choice is yours, but if you decide to go through with it, make sure to meet the guy in a public place first, like a Starbucks or something, somewhere in the public. Don't let yourself be alone with someone you don't know and who is going to get you naked and vulnerable. If, while in public with this guy, you don't feel comfortable, go no further.
That ticket is temporary. You will pay it off somehow and it will be gone. Nude pictures of you can last forever. Don't do what I did; don't put yourself in a position where you will not be in total control and may later regret what you did. And when I look back, that's all I really regret: that I wasn't really in control.
The beauty of youth is that you are, well, beautiful. The danger of youth is that you are often wanting the approval of people, and this will lead you to do things you will regret a decade down the line.
With me, with the career I've chosen, I don't think my photos will come back to haunt me. First of all, I never signed a release, so if they get published I can sue. Thankfully, I'm not as hung as you, bro, nothing so spectacular.
Perhaps the main point is this: in this sexually pent-up society, posing nude can have negative consequences for one's future. You don't want to make such a potentially risky decision while in a place of insecurity, which it appears you are. If you need money, I'm sure there are other wasys to get it, ways you won't regret 10 years from now. Working at McDonalds ain't great, but ten years from now it is not a potential source of embarrassment for you.