My daughter (6 years) lives in Germany. A representative of some service came to them in the house, communicating with their father in German. She approaches the guest and asks in German:
Are you Russian?
He responds in Russian, that yes, in Russian can communicate. She turns and leaves.
The father was guiding the guest and decided to ask how she managed to determine that the comrade was Russian.
The daughter says to him:
And he’s like you, daddy, sprinkling in German.