Do you call him a loser or a jerk? No? I thought not......You could kindly point out that seeing as you do not use those terms when addressing him, he could kindly not use them with you.
There are words in our house that are forbidden when addressing each other....."stupid", any swearing, derogatory comments and my worst word that makes my skin crawl - "shut up".
Maybe the next time your son calls you a jerk, live up to it and take away something of his or prevent him from attending something important to him. Respect is paramount in any household.
"If you say I am a jerk then watch me live up to it.......when you see how miserable you will be when I am actually a jerk, maybe you will appreciate it when I am not" Hah!!!
Sorry if I sound like a bit of a hard *** but thats the way I see it.......Good luck!