The late 'Cav the Nav' S&R instructor at Valley had a tale of his early training in Ansons. He was in the right hand seat and somewhat desperate for relief. The Anson had a drift sight fitted alongside the right seat and so, our hero removed the the drift sight and, kneeling on the seat, introduced 'Percy' into the mounting aperture. As we are all aware there is a venturi effect generated by airstream past such an aperture - and so it proved! The result was immediate and ( as he described it) extremely painful! Retrieval was even more so (Makes my eyes water to think of it!). A swift RTB was followed by a rapid visit to Sick Quarters (barely hidden mirth0 and a number of weeks of painful walking!.