Someone who sells their house during the red hot housing market to people lurking on Zillow waiting to pounce on any house, at any price and cashes in big.
Jon cashed out big selling his house online during the red hothousing market and became a Zillownaire.
To hump/fuck the shit out of something in a furious manner.
Originally sighted whilst observing the family K9 "Williow" the shit out of it's friend humpy bear, however living creatures can also be "Willowed".