For the first two years of wow, the APF sold their (at the time $50) rugs through Target.
Watson gets everything wrong and Holmes is then able to wow his friend with astonishing inferences.
And when we got the music I just thought, wow ... take me off the ceiling!
1510s, Scottish interjection, a natural expression of amazement. "This old interjection had a new popularity in the early 1900s and again during the 1960s and later" [DAS].
"overwhelm with delight or amazement," 1924, American English slang, from wow (interj.). Related: Wowed; wowing. Used as a noun meaning "unqualified success" since 1920.