The Law of "Fuck Yes or No" is applicable to dating, sex, relationships, even friendships. You may have absolutely nothing in common with that bartender. But they're hot and are interested in getting down. Is it a "Fuck Yes!" for sex? It is? Then game on.
Wrapped up in that sweet guy who treats you so well, except goes weeks without calling you and suddenly disappears after a couple drinks and a round of the horizontal polka? Been wondering if he really likes you? Do his excuses of being so busy all the time seem legit? It doesn't sound like the answer is a "Fuck yes." Then it's time to move on.
Making out with a girl at your house and every time you go to take her shirt off she swats your hands away? That is not a "Fuck Yes," my friend, therefore, it's a no and you shouldn't pressure her. The best sex is "Fuck Yes" sex — i.e., both people are shouting "Fuck Yes" as they hop between the sheets together. If she's not hopping, then there's no fucking.
(Hint Fellas: This is a great time to ask the girl why she's not comfortable, and what she's looking for from you. That, by itself — you know, treating her like a human and empathizing with her — often solves this "problem.")
Want to date that woman you met last weekend but she keeps ignoring your texts and calls? Not sure what to say or do, especially since she seemed so happy to go out with you when you initially met her? Well, my friend, this is obviously not a "Fuck Yes." Therefore, it is a "No." Delete her number and move on.
Fuck Yes or No applies to relationships as well. My girlfriend works with a guy who got married because "it seemed like the right thing to do." You do your taxes because "it's seems like the right thing to do." You wipe your infant's ass because "it seems like the right thing to do." You don't marry someone because "it seems like the right thing to do." You marry them because you can't fucking imagine ever not wanting to be with them.
Unsurprisingly, four years later, he was cheating on his wife every chance he got. The marriage was not a Fuck Yes for him, therefore it should have been a No.
Sometimes The Law of Fuck Yes or No will apply differently on different levels. You may be a "Fuck Yes" for friendship with someone, but mildly excited to have sex with them. Therefore, it's a no. You may be a "Fuck Yes" on banging someone's brains out, but a definite "No" on actually spending any time with them. Apply the law to your decision-making as it suits your needs.