What is means this sentence?
This joke made us cancer
I had got that comment, but I don't know what is meant for (I think it is idiom)!
I think you are referring to the meme: "X gave Y cancer"
RELATED: That Post Gave Me Cancer
is an image macro series commonly used in response to nonsensical or insubstantial posts submitted by the original poster (OP) or other users in a given thread. This hyperbolic expression implies that the content in question was so far below one’s expectation that it infected the reader with “cancer”, a slang term that is typically used to express one’s disgust towards a trend or a thread.
I've seen the "X gave Y cancer" meme used to provide ridicule, sarcasm, or sometimes just fun/comical effect.