When the characters assess their choices, they will always pick option 4 (which usually happens to be the joke option), nothing else.
Chapter 37 features a fairly casual build-up to Hori and Miyamura's first time. The scene then cuts away to the next day where a freaked out Miyamura is showing Shindou the full-on bite mark Hori left on the back of his neck to dissuade him from cutting his hair any shorter.
When Sengoku and Iura become curious about Miyamura refusing to bathe with them during their trip, Ishikawa lies, saying that Miyamura is... on his period, out of all things. In chapter 72, he later lies that Miyamura has a Chest Blaster. Interestingly, Sengoku and Iura accept both lies, with Sengoku even considering to accept the Chest Blaster theory as real in chapter 78.
Hori's reaction when the girls in class took an interest in Miyamura due to a magazine article. Starting with accidentally breaking a mechanical pencil
Miyamura's reaction when he saw his old friend, Shindo, talking to Hori:
In chapter 40 (chapter 169 of the original webcomic), Sengoku and Miyamura find out that all boys have to participate in the next swim class and desperately try to beg their English teacher, Mr. Yasuda, to talk the PE teacher, Mr. Sasaki, to let them sit out. Miyamura's reason for doing so is obviously because of his tattoos, while Sengoku is so incredibly skinny that he doesn't want to be seen in a swimsuit. Miyamura decides to go with Ishikawa's lie about menstruating, and if that wasn't enough, Sengoku's excuses take things Up to Eleven: he claims he will be a victim of a planned terrorist bombing and keeps praying for his right arm to be blown off.
The second part of Chapter 41, where Souta's friends are under the impression that Miyamura and Hori are his unhappily-married parents.
Yuki asking Tooru to be her pretend-boyfriend, and Hori and Miyamura's reaction to finding out that he's outclassed in every possible way by Yanagi.
In chapter 52, the scavenger hunt event takes place at the Sports Festival. Yoshikawa is assigned to find a "suspicious person" and immediately goes for Mr. Yasuda.
Miyamura is forced to take Sengoku's spot in the event, as he had ran away, and ends up competing with Hori. The two immediately pick Sengoku as their assignment, and after Sengoku grudgingly agrees to come with them, he asks them what they were supposed to find. Hori's paper reads "student council president", while Miyamura reads "a very skinny person."
Chapter 65: A series of them related to Hori's A-Cup Angst
Miyamura getting in trouble for elbowing her in the chest and thinking he hit her ribs, which makes Remi laugh when she hears about it and Yuki cry.
Hori then gropes Yuki and Sakura in anger that they are bigger.
The guys then get into a debate about the girls' chest sizes after Miyamura tries to defend Hori's chest size, with no one backing him up.
In Chapter 69, after Hori and Sengoku got locked in the student council room, Miyamura makes sure she was ok, and she assures him she was, she was with Sengoku. He then switches to asking Sengoku if he had been safe.
Miyamura, Ishikawa, and Iura spend the night at Sengoku's house in chapter 72, only for Sengoku to have no place to sleep because his room is cramped. During this time, Sengoku becomes curious as to why Miyamura doesn't take off his shirt, but Iura catches him when he's about to sneak a peek. When the boys wake Miyamura up the next morning, Ishikawa catches onto what Sengoku is doing, leading to more misunderstandings. In the end, Ishikawa manages to convince Sengoku and Iura to back off by... saying that Miyamura has a Chest Blaster.
The cold open of chapter 98 has Souta proudly showing off a paper he had to write for school about a family member. Much to the Hori family shock and distress he wrote it exclusively about Miyamura. Miyamura ends up sheepishly apologizing to them.
The cold open of chapter 102 has Hori and Miyamura going on a Double Date with Remi and Sengoku. Hori and Remi try to come up with names to use to reserve a table, where Remi wants to use Yanagi's name while Hori wants to use a combination of Sengoku and Miyamura's names. Miyamura gets confused when he hears both the names.
In the second part, the boys are hanging out at a restaurant and Ishikawa gets increasingly embarrassed by the couple-related drinks that the other boys order.
In chapter 115, Sengoku wants to be close friends with Yanagi, so Ishikawa suggests he playfully tickle him. Sengoku decides to practice on Ishikawa, only for Ishikawa to call him out as a molester, and Miyamura walks on him right when he does so. When Sengoku ends up finding out Yanagi knows a lot more about him than he thinks, things end up going well... only for Miyamura to bring up him being a "molester", causing Yanagi to become uncomfortable.
Chapter 120, when Hori gets on Miyamura, Yuki, and Ishikawa for failing to bring their stuff home slowly over time for graduation, Iura turns out to have actually done so. But then everyone realizes they had forgotten to give him CDs etc back, and then he is loaded down as well.