It's an idiom, suing isn't that common in Canada either. Basically "just try to stop me, because I know you can't, neeneer neeneer".

"I really don't care if you are offended or put off by what I said or did. The hyperbolic threat is meant to undermine how much importance another person is or may be giving something one did or said." https://idioms.thefreedictionary.com/So%2c+sue+me!