Willow looked at Jack, still laying on the floor, wondering how she didn't notice him before. She walked over to him and picked him up with a surprising amount of strength and moved him out of the way, waving her hand so that from an outside point, you couldn't see him. She then went to the kitchen and came out with a 'wet floor' sign and placed it near the invisible Jack so that people wouldn't trip over him when they couldn't see him.