A man went to a dentist one day for his regular check up. The dentist decided that one tooth was in such bad condition that it should be extracted. The dentist then advised the man of the situation who agreed to the procedure.
When the dentist went to give the man an injection the man said "don't worry, I don't need an injection". The dentist went on to explain that the procedure could be very painful, nevertheless the patient insisted that he would be OK without a needle.
The patient then went on to indicate that he had two experiences (in recent times) that had made him immune to pain, so the dentist went ahead and extracted the tooth and to the dentist's amazement the guy didn't even wince.
The dentist (quite astonished) remarked " that was amazing, the two recent experiences (you say you had) that made you immune to pain must have been something special, I'm intrigued would you care to tell me about them"?
The man said "sure, one day I was out hunting and suddenly had the overwhelming urge to evacuate my bowels. So I ducked behind a bush, squatted down and I can't believe I didn't see it, but my scrotum landed squarely on the trigger of a (spring loaded) rabbit trap and CRUNCH!!".
The dentist (imagining the scene and turning pale) exclaimed "oh my god, that must have been excruciating - how very unfortunate, but that was the first experience what was the second".
The man replied "when I ran out of chain"
Si thee