An Irish priest told me about the time he spent a semester at a seminary (yes, it's an 'i') in the US and scandalised his room-mate by asking for the loan of a 'rubber'. He was drawing a diagramme and wanted an eraser to 'rub out' an unwanted detail.

Scottish singer Jean Redpath used to tell one about the time she shocked a worker in a Californian hotel by asking him, 'Could you knock me up at 7 am?', meaning, 'please give me a wake up call'.