African-American Vernacular English
"...quite a few scholars have devoted careers to what they readily identify as a dialect of English spoken by black Americans.... It is considered wise in some circles to pretend that what we call “black” English is the same as white Southern English. However, this is pretending indeed. 
AAVE is a dialect of English characterized by non-rhoticity and several distinctive vowel mergers. Consonant clusters like /sp/, /st/, and /sk/ are reduced word finally, with the final element being deleted rather than the former, causing words to flow off the tongue more easily than Standard English. The cross-linguistically rare dental fricatives, /θ/ and /ð/, aka the TH sound, are shifted to /f d/ (which are much more common). For younger speakers, /skr/ also occurs in words that other varieties of English have /str/ so that, for example, "street" is pronounced [skrit], which is indeed more common than /str/, a rare and unusual cluster.