Hawk just tried to hit on Piper, his ex-girlfriend, Moon's girlfriend, and he failed, obviously. Piper and Moon kissed right in front of him, and he walked away heartbroken. You could see how hurt he was in his eyes. He depressed-fully walked to the counter and got himself a drink. He started walking to the couch, but he was looking down because of how hurt he was, so he accidentally bumped into you.