^A Peach-ified Bowser.
Toaddete (the Toad female counterpart) got an exclusive power up in the New Super Mario Bross deluxe, that turned her into a Peach-like "person", called Peachette. It raised a lot of eyebrows, both because of the lack of originality, and because it pretty much implied Peach herself might actually be a powered up Toad, so someone made Bowsette as a joke ... and it kind of exploded since then due to full effect of rule 34.
@ariacelesta: My headcanon is that the "thing" the glasses-girl was referring to with "Nankai" is "how many orgasms do you want". How she gave her those orgasms is probably irrelevant, because I've seen doujinshi where a person is driven to actual orgasm just via kissing because either the other person is just that damn good or the first person is hopped up on sensitivity-enhancing drugs/magic (willingly or not).