Context is king, this GAF, a gaming forum where gamers throw GOAT around like candy in halloween, when users enter the context of GAF it's not a stretch to think their minds adjust to equate GOAT to greatest of all time,as it's often used. Outside of GAF (or other formus) this probably doesnt happen.
G/A/F, or Germany/Australia/Florida. It's a GAF inside joke where people try to guess if said oddity comes from one of these locations, of which there are many that usually come out of them.
No. When it involves sex, its Germany. When it involves dangerous animals, it's Australia. When it involves having sex with animals, it's always Florida.