The phrase was initially used in the first episode of series 5, The Eleventh Hour, which aired April 3rd 2010. The Doctor says the phrase after his future travel partner, Amy Pond, critiques his outfit.
The eleventh incarnation of the Doctor, played by Matt Smith in the BBC’s long-running science-fiction series Doctor Who wears a bow tie as part of his outfit. The Doctor, in several episodes of Series 5 and 6, insists that “bow ties are cool”, explaining in “A Christmas Carol” that the bow tie is “cool” simply because people still trust him while he wears it.
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