twitch (someone's) nose

Translations
подергивать (чей-то) нос
He would often twitch his nose when he was nervous.
Он часто подергивал нос, когда нервничал.
Definitions
To twitch someone's nose means to make a quick, slight movement or to cause a small, involuntary contraction of the nose, often as a playful gesture or expression of annoyance.