chinny reckon

A phrase, probably of playground origin, indicating disbelief or incredulity. Usually, but not always, accompanied by a scratching or vigourous rubbing of the chin. Variants include "Itchy chin" and "Spin-n-n-n". Reference is occasionally made to Jimmy Hill when performing this maneouvre.

There are many regional variations such as the Scottish "och, and Forty Deafies".

Also used in offices (which, let's face it are just glorified playgrounds in many cases).

This is probably based on its renaissance, courtesey of Rob Newman and David Baddiel, and the other two who weren't as funny (Steve Dennis and Hugh Punt, or was it Steve Punt and Hugh Dennis) off TV's The Mary Whitehouse Experience, who used the variation:

"Oooh, my beard is itchy"

Accompanied by the aforementioned furious rubbing of the lower chin, of course.

And let's not forget the all important pronunciation of reckon as "reck-on", rather than "reckun."