Well, it could be about Sakura hiding under a desk during a pop - up dangerous situation in the Naruto world. Maybe she's using her medical skills secretly to help an injured comrade while under the desk.
It could be Orochimaru. He might be after some valuable information that Sakura has and she has to hide under the desk to avoid him. The 'pop' could be one of his experimental creatures suddenly showing up.
One possible plot could be that Naruto and Sakura are hiding under a desk during a dangerous situation in the ninja village. Maybe they are on a mission and things go wrong, and they have to take cover under the desk while they plan their next move.
Their relationship could develop in a more intimate way. Being in such a confined space like under the desk forces them to be closer physically. This might lead to them being more aware of each other's presence and start to see each other in a different light. For example, Naruto might notice Sakura's little nervous habits and find them endearing.
It could be the Slytherins. They are often portrayed as the antagonists in the Harry Potter series. Maybe they're jealous of Hermione's intelligence and want to embarrass her by forcing her under the desk.
I'm not sure there's an official fanfic with such a specific title. However, if it were to exist, it might be about Naruto and Sakura in a situation where there's some sort of emotional outburst (the moan part) related to a desk and perhaps the idea of a fiance. It could be a very creative and unique take on their relationship, exploring new aspects of their bond in a fictional scenario.
In this fanfiction, it could also be that Hermione is forced under the desk as part of a mystery. There could be some hidden secrets or clues under the desk that she needs to discover, but she's being forced to stay there against her will at first. As she investigates, she uncovers something that has far - reaching implications for the wizarding world.
One possibility is that this is a misnomer or a very tongue - in - cheek title. In the fanfiction, it could be that Harry is using some new form of magic under Snape's desk that has an effect that can be humorously described as'sucking'. For instance, he could be using a spell to draw out negative magical energy that has accumulated under Snape's desk, which is causing problems in the classroom, and the spell's action makes it seem like he's'sucking' something out.
The novels about the man serving the woman under the desk generally belonged to the romance, love, or urban emotional novels. The plot might describe a man working in a company to cater to the needs of the female lead, providing various services after work, and finally the relationship between the two gradually warmed up. This type of novel often involved topics such as workplace, love, marriage, family, etc. It had a certain practical significance and enlightenment.