Don't tell me that no one else have asked their friends to try strangling them. Erotic asphyxiation is pretty common. I mean as long as you don't compress the carotid arteries at the sides too much it should be fine. I've heard that a common technique in kubishime involves the upwards pushing and tightening of said arteries to grant swift death.
Shishou gives Miss. Sunflower books that were supposedly recommended to her by the previous Miss. Sunflower. Within the stack of books, Shishou snuck in a raunchy yuri novel (age gap, student teacher) as a joke. Naturally, since Miss. Sunflower wants to be like her predecessor, she reads all of them. This was however, the first time she had ever been exposed to such lewdness and develops a strange sense of arousal especially when the relationship between the characters in the novel resemble that of her and the previous Miss. Sunflower as well as Matsuri. When Matsuri arrives the next day, she begins to act self-conscious of their interactions until Matsuri finally confronts her and stuff happens.