Deffo Jeffo 

It means Definitely. Deffo is short hand for Definitely, just add a Jeffo for coolness!

Q 'You want to go to the movies?'
A 'Deffo Jeffo!'

Deffo Jeffo by rachcook182 March 21, 2007

deffo jeffo 

an longer version of definitely, usually to a person to person with a name like jefferson or geoff.

person 1.we should defo go to the the rave
person 2.yeah deffo jeffo

deffo jeffo by work colleague April 19, 2011