1."defo" is a slang term used for Deforest which is a small village just north of Madison,Wisconsin. Mainly used by people from Deforest or someone else in the area in reference to Deforest.
2.an area where alcoholics and drug addicts are from
Ah, no shit man, you're from defo? What year did you graduate?
That guy is super faded, he must be from defo!
Damn Bryan you're fucked up like defo stats son!