Invisible pants
From Jenny Everywhere Wiki
A pair of “invisible pants”, tight leggings which made their wearer invisible from the waist down to the ankles, was one of the items accumulated in the closet of Jenny's apartment in one universe. When she and Kim went through the closet to sort its contents, they found it again and Jenny, amused at her own statement, pointed out that she'd been looking for them. (PROSE: Cleaning Day)
Behind the scenes
Whether the invisible pants are technological or magical is not clarified within Cleaning Day.