We all have fantasies of fighting fire with fire, when we deal with an abusive, upset, or otherwise nasty customer, and it seems unfair that we aren't "allowed" to fight back. And, we all have the fantasy of thinking we can find that ONE special phrase or putdown to get a customer to back down, or feel small.
The problem is that you can't really "hurt" the customer. The customer may be angry, and even if you "win", by insulting back, YOU will end up paying the price, through complaints to your manager, feeling stupid and suckered later on, etc. There's also a risk of phsyical violence if you insult back and push the customer "over the edge".
In this video, which contains a few comic insults TO customers coming from Chef Gordon Ramsay, you'll be able to indulge the fantasy, and have a few chuckles, but it's poor practice.