Ben Affleck -- Thank God ... The Back Tattoo's Fake

We're not anti-tattoo or anything, for sure, but praise the Lord Ben Affleck's gnarly back tattoo is removable.

Ben told "Extra" the Phoenix back tat is for a movie role, and comes off easy.

Jennifer Garner was vague about the ink, saying, "Bless his heart." Ex-GF Jennifer Lopez was more direct, calling it "awful."