Enron was constantly in the news at that time due to their scandal which led to their bankruptcy. Some executives were found guilty of wrongdoings, and a few were even sentenced to prison. Lots of people lost a lot of money and their shareholders were very angry about it. So the company was made out to be 'the bad guy' and portrayed as a greedy corporation on television, newspapers, etc.
The joke in this context is that Chandler jumped on the bandwagon and blamed Enron, even though his problems had absolutely nothing to do with Enron, and also despite the fact that he didn't understand anything about the scandal.
Hope that helps.