Learning a language is tough. Not only do you struggle through a dense new jungle of vocabulary, subject-verb agreements and third conditionals, you also have to contend with smug native speakers sniggering when you say something slightly wrong that gives it an amusing double entendre.
People learning German, for example, always have to remember the difference between "schwül" (humid) and "schwul" (gay) – one dropped umlaut and you can end up in a very sticky situation.
But Germans learning English also have a few land-mines to avoid - some are annoying, others can brighten up a dull day. Please.