There's only one moment of rape in the show: when Kelso is raped by Laurie in "Red's Last Day" (S2E02). Here's a clip: L
Kelso and Jackie have recently gotten back together, and he is having a fantasy where he tells Paul Anka and Lyle Waggoner that "I love Jackie and a real man can deny his instincts," when Laurie interrupts him.
KELSO: Listen...Laurie....uhhh I don’t think you should be in here...I mean I know we’ve made out a couple dozen times...
KELSO: Okay....but that’s over!
LAURIE (climbs on top of Kelso): Gosh, I sure do feel close to you Kelso!
KELSO: Uhhhhh, listen, Laurie, I, I don’t think my girlfriend, ... Jackie, would like you sitting on me.
LAURIE: I think YOU like me sitting on you, in fact I know you do!
KELSO: Okay! But that’s not the point!
LAURIE kisses Kelso: Shut up Kelso! This is your lucky day.
(She closes the door. Cut to the van seen from above)
KELSO: Those are my pants! No! .....(van starts shaking) yes....yes....
Although Kelso sexually desires Laurie, he doesn't give his permission because he knows it would hurt his relationship with Jackie. Laurie forces him--granted, it takes little force, but he distinctly says no. That's rape. In traditional thinking of just 20 years ago, this wouldn't count as rape at all, and even today you'd have a hard time convincing a jury. It's still rape.
If you don't think this is rape, imagine how it would play out with the roles reversed. What if Laurie had gotten a new van and was day-dreaming about its potential when Kelso came along? What if she became uncomfortable, and he told her to relax as he shut the door and told her it was her lucky day? What if Kelso unzipped her pants and she said no? Is it rape? Even if right afterwards she says yes?
Look, rape isn't a question of sexual desire. You can want sex and still be raped. Wanting isn't the same thing as consenting. If a woman goes to a bar wanting to have sex, she doesn't want to have sex with just anyone. So she may leave the bar, sexually frustrated, though she has turned down a man's advances. That doesn't give him the right to force himself on her. Even if he makes her orgasm.
As it turns out, he doesn't mind. In fact, he really liked it. When he announces in the circle that he and Laurie have had sex, he's bragging and gives it two thumbs up.
KELSO: I mean...she took advantage of me! I’m violated.
HYDE: You idiot, your thumbs are still up!
KELSO: (Chuckle) Acting’s hard.
And that's what gets me. His example suggests that (1) rape isn't really rape and (2) rape isn't a big deal. When Fez suggests the dark room switch in S7E22, Angie laughs at him good-naturedly. But pretending to be someone else in order to have sex does, in fact, count as rape. Fez is an admitted pervert, so it's "natural" that he has these plans, and it's women's job just to laugh them off.
In the world of That 70s Show, it's easy to laugh at rape threats, because women are presented as having all the power. Think back to seasons one and two when Donna would "playfully" say okay to sex, then rescind her permission. It frustrated Eric, but he never took advantage of her semi-consent. Because she held the power in the relationship. There are many other examples and I'll post some later if I get a chance--if I can tear myself away from watching the show.
As much as I critique this show, I love it profoundly.