The narrator tells us that she's going to a beach with a bunch of other girls for a summer vacation. She's super excited about it, but she also knows that it's a bad idea to have sex while on vacation. The narrator asks the girl if she thinks she can stop having sex just because the beach is summer vacation, and the girl says she can't, because she'd rather have sex all the time. She also tells the girl that if Mr. Tsuji finds out, she'll have to tell him about it. But first, the narrator wants to make sure that the girl is faithful. She wants to show the girl how to "slop knock" and "swallow knock" so that she won't be able to get away with having sex during the summer. The girl is so excited that she doesn't even notice that the narrator