What’s Poppin? Jack Harlow will be joining the WOO HAH! Line up in 2021. The young rapper made his introduction to the rap game with a pair of fan favorite independent mixtapes. Harlow’s breakthrough was made definitive after the release of Platinum-certified hit ‘WHATS POPPIN.’ After the taste of a chart topping hit Jack is hungry for more and we can’t wait to see what he has in store for us.