Up until around the age of
12 this is a common phrase in every child'
s vocabulary. Used to question the validity of somebody's statement. In cambridgeshire there were two variations of chinny reckon or "Chinny
Rah-Kon". Firstly one would put their tongue imbetween their
bottom teeth and lip, making it swell, and make a low noise before saying "Chinny Reckon" or "Itchy Chin". The phrase "Chin Spin" was also used in the same context.