The joke was:
We go somehow with the chore (his name is Dan, he is a teacher at school) through the dark courtyard at 10 p.m. It is dark. I watched a hop-stop company. I think we need to prepare for the worst. We pass by them, and from the crowd (chapter 15) it is said “Hello, Denis Viktorovich!” and he replies “Hello, young people.” I am confused (what whispered) "who is this?" and in response Dan says quietly "this is my studio". I am crying :)