Clapham bow tie 

Wearing a rear bicycle light in the same manner as one would wear a bow-tie. Light is generally attached using a clip to the collar. Light is switched on/off as desired. Must be flashing when on.

'I say Jenkins, that chap is sporting a rather fine clapham bow tie, what?'

'Eeey blud, set me your clapham bow tie. Also your phone.'

Clapham bow tie by Dr. Lady Lolbert Monkeybush March 19, 2009

Clapham Bow-Tie 

The act of wearing a flashing red bike light on the collar of your shirt in a similar manner to a bow-tie.

"I am going to a rave tonight. I had better not forget my Clapham bow-tie"

Clapham Bow-Tie by Domingo Cortez March 19, 2009