This

mom

"Is she really a mom of this whole gang? It might be... or... An alternative version: Nikolette Ivanova and her two little monsters, and Evstigney Gumnov and his two gremlins, are sneaking off to the park behind their spouses' backs. Evstigney asks his kids 'Don't tell Mom we saw Aunt Nikolette,' and Nikolette says the same thing to her children. Because Nikolette and Evstigney are secret lovers.

This actually a sort of happened to me when I was a kid. I was visiting my uncle in another town (in Georgia), and we met a woman and her daughter in the park to spend time together. Later, I told my aunt about the meeting, and this caused a huge scandal... Turns out that girl was actually my secret cousin!