My favourite way of talking about rape is actually by talking about sex. I do NOT think rape is like sex, but I think that a lot of the rape myths that permeate our rape culture DOES make this connection .So I say to people: how you think about sex affects how you think about rape. If you want to never, ever, ever rape someone: listen closely!
Scenario 1
if you think of sex like a competitive thing, like a game - say, like football, where the man is trying to score a goal, and the woman is trying to 'defend' the goal and stop him scoring - if you see sex as somehow adversarial (which our society does, in it's language - score, pull, 'give it up') then it is possible to see rape as an extension of sex. It's just playing a little dirty, being a little coercive, maybe a slight foul or some elbowing but hey, goal scored and that's the point, right? Winning is what counts, right?
Scenario 2
If you think about sex like pleasurable and co-operative activity, like a jam session, say two friends with guitars or someone playing the piano so that another can sing... then the only way you can 'win' is if you both have a good time. That's it. There's no 'foul' possible, because then you're not both having a good time. Can you imagine sticking a gun to someone's head and forcing them to build play jazz with you? Cos I can't. Cos the point of the activity is mutual pleasure, and there's no 'winner' -or rather, they are both winners, and there is no loser in this scenario.
That's how I think we talk about rape and rape culture, and teach our kids not to rape. I will be telling DS this over and over and over as he enters his teens, until he dies of shame and becomes a monk. Or an awesome, thoughtful partner to someone. 
Analogy stolen from Amanda Marcotte at Pandagon.net, btw. I just can't, with a cursory google, find it.