From this page:
Spillage drag, as the name implies, occurs when an inlet "spills" air around the outside instead of conducting the air to the compressor face. The amount of air that goes through the inlet is set by the engine and can change with altitude and throttle setting. The inlet is usually sized to pass the maximum airflow that the engine can ever demand and, for all other conditions, the inlet will spill the difference between the actual engine airflow and the maximum air demanded. As the air is spilled over the external cowl lip, the air is accelerated and the pressure decreases. This produces a lip suction effect, which partially cancels out the drag due to spilling.
I understand most of the above, except starting from "This produces a lip suction effect..."
If I'm getting this right, the unwanted air, stuck in the inlet, leaves the inlet moving forward, spills out, sucking the airframe with it, thus negating some of the drag caused by the spillage?