1) When the muscle of one arm is pumped up due to too much masturbation.
2) When one arm is aching because of too much masturbation.
3) When one arm is aching due to the repeated performance of a task such as sanding down a piece of wood.
A small piece of information. Derived from the word ken, used often in the scottish language and is synonymous with knowledge.
Person 1: "Hey I don't get this shit. How do you solve this problem?"
Person 2: "I got that one. Give me some kenlets on this assignment and I'll help you w/ that one."