pisser

A person (usually male), who makes a social media comments designed solely to nitpick and negate something another person (usually a woman) has said - much like a dog that feel compelled to piss on other people's things

Every time I post a How-to example on Facebook, that pisser, Matthew, shows up and nitpicks something not relevant to the topic

I was having a a lovely twitter conversation until that pisser, John, showed up.