Cockpit vacuum cleaner................we certainly had them on Shackletons. Every self-respecting flight-engineer created the device by cutting a "letter-box" slot in the head of a used 1.75 flare tube and attaching a length of oxygen tubing to the open end. When inserted into the very pistol aperture, it became either a fantastic cooling airflow - slot facing forward, or a super device for emptying the armrest ashtrays - slot facing aft.
I think I've still got mine somewhere in the garage !