The Best of Frasier Crane

Does anyone know where the word “shampoo” came from? According to the dictionary, it’s meaning is “Any of various liquid or cream preparations of soap or detergent used to wash the hair and scalp.” From this I would expect a soft, clean word. But when you break down “shampoo”, I see sham, which means trick, therein lending itself to “tricky”. And the second half of it is another word for “shit.” So basically the word means “tricky shit”, which is ironic cuz shampoo is the gold standard for simplicity: rinse, lather, repeat. Hmm.