Touching your hair
You do it so often that you don't even notice you're doing it. But if you can't stop touching your hair whilst you're talking to somebody, for example, it could mean that you have a desire to keep the outside world at a distance.
This habit is common among introverts as a way to reassure yourself or to manage stress. It can also be seen as flirty if you're doing it on a date.
Biting your lip
Biting your upper lip is a sign of stress or sadness. Biting your lower lip, on the other hand, can be seen as an erotic gesture which suggests a desire to charm.
Biting your nails
Especially common among young people, about 1 in 3 people either bite or pick their nails. It's often linked to stress or anxiety but also to boredom and lack of self-esteem.
Cracking your knuckles
Cracking your knuckles is often used to relieve anxiety or tension, as the "click" sound can have a calming, satisfying effect. And despite what you might have heard, it has never been proven that cracking your knuckles can lead to arthritis.
Fiddling with objects
If you can't stop yourself from fiddling with things whilst you're talking to someone, whether that's peeling the label off a bottle or tearing up a paper napkin, this suggests that you have some kind of instability, stress or feeling that you are misunderstood. It can also suggest sexual frustration.