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Mike, I try to choose my words carefully!
I said it was silly, not wrong (this because I certainly I couldn't be bothered to check it, and in any case vaguely remembered it). I still don't...

That one is silly, especially since hippo means horse :)

anyway for medical ones, I always heard:

pneumonoultramicroscopicsilicovolcanoconiosis

My favourite 'everyday' long Russian word is probably достопримечательностями :)
преподавательницами also amuses me for some reason.
Sure there's zillions of much longer ones though.