What are the hardest words to spell in the English language ?

And what are the strangest words to pronounce. Im a TEFL teacher and I would like some examples to make my classes a little more interesting. I currently use Loughborough,Knightsbridgeand Belvoir Castle(pronounced Beaver which always makes me laugh).
Update: Spelling for Life , shouldnt that be, they are all real words? Thats funny.Spelling is pretty useless if you dont know what your going on about . lol.
Update 2: Welsh words dont count.
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