Slang noun used and understood primarily by Brummies (people from Birmingham, UK), Yam Yams (people from the nearby area of the Black Country) and other Midlanders.
It is a noun used to describe the action of rolling forwards on the ground. It is often described as a 'forward roll' by the rest of the country.
Brummies will often say 'gambowl' instead of 'forward roll' and very few people outside of the city seem to understand this term.
The spelling of gambowl is a debate in itself, as it is rarely written and mostly used in speech. Variations of this spelling (gambowl) include: gambole, gambol and gamboul.
There is a Facebook group campaigning to promote awareness of the word, entitled 'it's not a foward roll, it's a ******* gambowl'.
That was a very nice gambowl you did just now.
(That was a very nice 'forward roll' you did just now.)
These gymnasts haven't done any gambowls yet!
(These gymnasts haven't done any 'forward rolls' yet!)