Hehe, I'm doing it again, starting with Sans and Frisk doing pranks as friends (obviously).
I don't know what they could have done and to who exactly but it was both hilarious and risky enough for them to try not to be found while having a hard time being silent.
I'll let your imaginition do the job, I'll try to do the other days not too late.
undyne is sooooo funny cause the entire game she's catastrophically down bad for this 4'9 reddit tgirl who's convinced she's unlovable so she'll openly call her cute to her face whenever they meet and dress her up in little outfits and call her to ask about the weather (they live in a cave) to no fucking avail and then crash on papyrus' couch to spew her romantic dyke woes to him only for HIM to be like "YEAH THIS IS A NORMAL BOSS-EMPLOYEE RAPPORT". 360 degrees of relationship hell with this woman. no wonder she's insane