It means : “holier-than-thou: excessively or hypocritically pious”.

You’re probably full of yourself and comment on other people’s statements like it is your birthright to tell them how you know their profession better, how they should be raising their kids, how they should be holding their posture and who they should be hiring for that job opening.

If you are sanctimonious, you are probably also pedantic : “A pedant is a person who is overly concerned with formalism and precision; marked by a narrow focus on or display of learning especially its trivial aspects”. And you will obviously also be patronizing : “characteristic of those who treat others with condescension”.

I, on the other hand, prefer to be like Calvin. I don’t know shit and I only claim to know shit. I also want you to fuck off. Fuckface. Thank you Russell, I love you too.