Do you really think I've lived among humans for tens of thousands of years and haven't once tried anal sex? Please-- I've done things that would make a succubus blush!

[This is not the source of Mephisto's shame here, okay.]

But honestly-- as if I would have ever slept with my own human host, let alone gone to the effort of seducing him! That's just inappropriate! Like some sort of bizarre masturbation, but twice as pathetic!

[...of course, the implication going unsaid here is that he's definitely the Mephistopheles mentioned in the story.]