I'm not entirely sure what the OP was referring to, either; since they said "the princess", I assumed it was Nastizia's trials, and from "frog" I assumed they meant the 5th trial which features a non-sapient alien pet that's kind of like a frog-lion hybrid (or something; it definitely has frog-like elements to it), though the "not fuck" bit confused me. Now that you mention it, I can see that some people who aren't too familiar with the lore might mistake rahn for frog-like people; if so, that means they're referring to the 3rd trial. Passing that requires at least 60% Willpower, to not have maxed out Lust, and to pick Decline.