The letter gimel ג has the meaning of a 'rich man chasing after a poor man' (1) and camel is gamal גמל , an obvious pun.
The rich young ruler had just chased after Jesus (a poor man) and played a game of threading the needle. This is where the law is defined by the individual so that he finds himself narrowly avoiding a violation of the law in his own eyes. Jesus had just told him that by Jesus's definition of the law there were none good:
- 17 And he said unto him, Why callest thou me good? there is none good but one, that is, God: but if thou wilt enter into life, keep the commandments.
His response is that he has kept the commandements:
- 20 The young man saith unto him, All these things have I kept from my youth up:
It is apparent that his definition of the law justifies him, where Jesus's definition of the law makes no one good but God.
It takes great justifications to say "I am worthy" when standing before God.
So the camel had just threaded the needle of the law. By making the rich man into a camel by way of the pun, Jesus was mocking the attempt at self-justification. What was easy for the rich man, so he thought, was proclaimed by Jesus to be an impossibility by the pun.
(1) "Our Sages teach that the gimel symbolizes a rich man running after a poor man," http://www.inner.org/hebleter/GIMMEL.HTM