Here's an introduction to a common skill in Furoticon: Frigid.
Frigid to X means: "When it's in play, this object can't be pleasured by X. If only X is swinging, this object can't put out." where X is any sort of modifier, like Males, Females, Treats, etc. (For ease of understanding, the last part has been reworded as "If all swinging Furres are X, this Furre can't put out.")
Okay, that is just a little confusing. Frigid is actually two skills in one. The first part is fairly simple: "When it's in play, this object can't be pleasured by X." Let's take a look at an iconic Frigid card, The Gay:
Gayin' it up.
The Gay is Frigid to Female Furres. Thus the first part of the Frigid skill means that The Gay will always take 0 pleasure from Female Furres. So if you're playing against a harem of Females, The Gay is a good choice for your harem, because when he swings in, he'll be nice, he'll mingle with the ladies, maybe grab a few boobs, but ultimately it will be unsatisfying for him. Even if five ladies put out to him, he'll take no pleasure from it.
Sounds a little overpowered? Well, that's where the second part of Frigid comes into play: "If only Female Furres are swinging, this Furre can't put out."
Let's reverse the previous example. Say five ladies are swinging at you, and all you have is The Gay in play. The Gay looks at all those ladies and can't find a single cock to occupy his mouth, so he says, "No way." He turns to you and says, "They're all yours. Have fun." The Gay refuses to put out, leaving you to take the pleasure of all five girls.
If four girls and a guy were swinging at you, however, The Gay would happily get into bed and take the pleasure for you. He just wants some cock, after all!
And that's all there is to know about Frigid!
...except one last thing: What about multi-gendered Furres? Say you have The Hetero and The Gay in play and your opponent controls Lucas and Rose:
Lucas and Rose are a Male/Female Furre, so if only Lucas and Rose are swinging, neither The Gay nor The Hetero can put out.
The Gay would be like, "Not if she's joining us." And The Hetero would be like, "Not if he's joining us."
But if you swing with The Hetero and The Gay, and they're met with Lucas and Rose, then the cheetah boys will give pleasure, but they'll be, like, "Uhh, this is awkward," and not receive any pleasure.
You can find all of these cards in 2nd Vanilla Booster Packs!