How we change what others think, feel, believe and do
Tongue body language
The tongue is normally important in spoken body language. In practice it can also send some body language non-verbal signals.
A deliberate gesture of sticking out the tongue at a person is impolite, although considered rather childish and thus reflects as much on the person doing it. The gesture thus appears petulant unless it is done in an amusingly cheeky way. The rest of the face should indicate more of the intent. Cheeky tongue-poking is often followed by a smile or laughter.
Sticking out the tongue also can happen when the person is trying hard to do something. When this happens it traditionally appears at the side of the mouth.
When people are talking in romantic setting, sticking out the tongue can be a sign of lust.
The tongue can be used to lick. By oneself, pretty much the only thing the tongue can lick is the lips (although a more hidden way of this is licking the teeth).
Lip-licking may indicate desire, perhaps for another person and perhaps for food. Usually it is for what is in front of the licker.
Licking lips can also be an indicator of stress as the effects of tension reduce saliva flow and dry out the mouth.
As a deliberate signal to others it can be sexually enticing, saying 'I would like to like you'. As such, it can be very arousing, particularly when done slowly and with other flirting signals such as a slightly lowered head and steady gaze.
Licking another person can be extremely arousing and is typically done either as a part of foreplay or as a quick tease.
Biting the tongue typically indicates that the biter wants to say something but somehow feels unable or unwilling to say what they want, perhaps for fear of offending or breaking social rules.
With mouth closed and tongue inside the mouth, you can still sometimes see what it is doing, although this is a hidden action and often the person themself does not realize they are doing this.
Pressed against the cheek it can indicate thinking and uncertainty. This can also indicate contempt and a form of duper's delight, especially when done briefly.
Pushed in front of the teeth, pushing out the lips, can also indicate uncertainty.