The evening's entertainment

Clara: Tonight the sandlady will come to you.
Chris: Not the sandman?
Clara: No!
Chris: Why not?
Clara: Because he's at home entertaining his kids!
Chris: Ahhhh, and will the sandlady come to you, too?
Clara: No!
Chris: No? Why not?
Clara: Because I'm not tired!

Epilogue:

Clara: The sandman goes to bed in the morning, when the sun comes up.
Tanja: Why?
Clara: Because he has to work all night, so in the morning he's tired!