Right arm longer than left - your pic - did you photoshop it ??
It is likely a form of "Fiddler Crab Syndrome" due to heavy groin-play (self or otherwise) many men get one arm noticeably larger (like a Fiddler Crabs large claw) than the other.

The length is due to heavy use in "reacharound" movements which often stretches tendons, bones
and muscles.
When bhanky does "the crab" he is likely thinking of homo-erotic moments in his colorful past. His extensive use of the "Crushers of Cock" sphincter strengthening "Mananas" to perfect his turd-cutter's power over the penis is the stuff of glory-hole legend.
