Term used for someone who screws up your evening plans. You spend all day planning and get all excited then a screwba tells you politely that they don't feel like it anymore.
Person A: "Yo I'm soooo excited for tonite. I can't wait to get plastered."
Person B: "Actually I'm tired, I'm just gonna go home."
Person A: "What? You were all excited 5 minutes ago."
Person B: "Sorry dude, not feeling it."
Person A:" You're such a freakin screwba