You all have us, but you don't know why.
We all have cheeks, but their uses are not as instantly obvious as those of other body parts.
Our much more useful cousins are waiting right nearby
Teeth, on the other hand have very obvious uses.
We can't do much, but we're sensitive things.
Cheeks are very sensitive, having many nerve endings.
We can hardly stand up to the abuse that you bring.
You run us straight through without second thought.
You pass food, alcohol, cigarettes - all sorts! - between them. Often pretty much on auto-pilot while eating.
Do you stop when we ask? Sadly not.
Cheeks can 'ask' since they are important for speech and shaping particular sounds.
You bite us, you pull us, you stretch us to our limits.
You can bite, pull and stretch your cheeks.
But we don't put up a fight, we willingly submit.
But you know what, they put up with it and keep doing their jobs!
The title is also a clue, since:
'Cheek' is a synonym for 'abuse'!