There is a growing trend which involves bluffing car owners in order to squeeze out some cash. 
When you go to inflate your tyres at a tyre refilling shop, the repairer observes the level of your alertness closely and may arouse your suspicion that one of your tyres has a leak. Obviously you would not like to take a chance of driving any further.
Next he would insist you relax inside the car as he is confident that he could mend the said leak in a jiffy. And while you are seated inside, he would seek your consent to help you with his benevolence! 
And with your consent, he would mend it within a few seconds – without taking the trouble of opening the wheel from the axle. You would then thank him and your stars at having been saved by providence and the kindly mechanic from an inevitable disaster and leave after payment.
Beware! This is the most innovative sales gimmick of the tyre repair vendor these days. If you ever come across such a warning from a tyre repairer, do not allow him to punch your tyre unless you get out of your vehicle and have examined it yourself. In most of the cases you would find that nothing really has happened to your tyre in spite of him trying to plant the suspicion. If your tyre looks alright, do not pay any heed to his tricks and drive on. It would save you from an unnecessary damage to your tyre and a few bucks.