Green’s Dictionary of Slang

a detachable bow tie.

1973		H. Leonard Da (1981) Act I: I was dining out in London: black dickie-bow.
1977		A. Bleasdale Who’s Been Sleeping in my Bed 100: I’m havin’ second thoughts about me dickey bow [...] It’s hurtin’ me neck.
2000		M. Manning Get Your Cock Out 28: The band were waved through the door of the himmler Hotel by silverback gorillas in shades and dickbows.