I've actually done this a couple of times..
One of my best ..At our company Christmas party years ago it was always at our owners Daughters house ( She was the accounts receivable) she was always dressed to the nines and very proper. She had a big house and always over decorated with Christmas.. In her front Bathroom I placed a BBC "big black cock" in the cabinet directly across from the toilet.. stood it up proud ... How many women sitting there on the toilet peered into that cabinet out of curiosity I don't know... but at the end of the night we all got a good laugh..