Thank you! The writing on the drinking game was intentionally left ambiguous for people to fill in what they think what Katsu and Chie asked Tsukasa about. I don't think I will write something that explains it, mostly because I have no experiences with alcohol like that, alcohol tastes bad anyways and I can't imagine myself or anyone for that matter drinking it. But that's just me. Sorry, anon!

However, I can tell you how I though the night started: In my head, it started with a simple, "What do you think of Tokyo Arkland?" And a "You, Rui and Asahi seem pretty close, how did you guys meet?" Both of with Tsukasa answered, but when it came time to tell them how he felt about Asahi and Sakurako as people, Tsukasa started to drink more as I believe that he didn't want to say anything that could be interpreted as bad and start anything, especially when at an event for Rui. At that point in the story, the failed rooftop confession was fresh in his mind so he wouldn't have liked thinking back on his high school days anyhow.

Both Katsu and Chie as mischievous people and once they saw that Tsukasa didn't like to answer questions about his past, they decided to tease him for it and ask more questions about him and Rui back when they attended school together. To which Tsukasa didn't want to answer more and more and... Well... You know what happened.

I hope this answers your question!