Th-fronting's a merger of the pronunciation of the English "th" with other sounds, that occurs (historically independently) in Cockney, Newfoundland English, African American Vernacular English, Liberian English, and more recently Estuary English (though the details differ among those accents), by which Early Modern English /θ, ð/ merge with /f, v/. Apparently, no accents with the merger completely merge the phonemes, because virtually all speakers of such accents know which words shou… (More on Th-fronting)