Call the union. Racial jokes are illegal in a Canadian workforce. You can get him charged and/or fired. Also the call can be anonymous

Your boss is an ass for laughing at a Holocaust "joke", but YDI for saying pissed in front of a client. You are at work, the client who made the Holocaust "joke" wasn't, it is your job to be professional, not the client's. It may seem lame, but it is a work place, keep it clean, even if your clients don't.

Yeah, well even if you don't agree with the joke, a client may get a laugh from your boss since that client is spending money with your company. Doesn't mean your boss agrees with it. You, however represent his company, so using foul language in front of a client is very unprofessional.

always impress the clients.

Because there is a WORLD of difference between laughing at a client's joke and using foul language in front of a client. Even if his laughing was sincere, it's still a good business decision to make clients feel good, while sounding unprofessional in front of clients is exactly the opposite. Maybe, instead of deciding what your boss will and won't accept, why don't you just act professional with every client?

Sorry man, but the customer is always right and you are not