Mansplain

man-splain (mn-spln)*

verb/slang
1. To explain accurately or inaccurately with total confidence that your audience will accept your mansplanation on the grounds that you are a man** or superior in some way.
When I first met Tom, he was taking a class that Lisa was teaching on the History of Science. Despite the fact that he registered in her class and still hadn't finished an undergrad degree, he had to waste everyone's time twice a week, mansplaining how Lisa had it all wrong.

Synonyms: being a pompous dick.

*This term is an humourous combination of the words man and explain and was created to quickly describe the behaviour of male newbies to internet forums frequented by women.

**Either sex can be guilty of mansplaining. In fact, I do it in this blog ALL the time :)