P Tube Testing.
It never occurred to us TPs at Boscombe Down to flight test those tubes in the Vs. It would have been an interesting trials instruction. Nor have I ever tried to find a design specification for male/female tubes.
Had to occasionally use the 'little' funnel in Mustangs during a long haul. The associated tubing came out under the tail and it was possible for its end to be turned around into the airflow. Pre-flights would reveal if any ground crew had developed a grudge.