Most Caucasians have close friends of other ethnicities. Every ethnicity has their own dialect/informal way of speaking free of the onerous bounds of grammar. All Americans are familiar with the Cajun dialect which sounds very coarse and abrasive to this writer.
What is important to understand is that we ALL speak dialects of English. A dialect is just a particular rendering of English informally in a certain region or practiced by a certain group. Racist Whites sometimes spoke derisively about jive talking Black people back in the 60s, but today the racially neutral terms are Ebonics(origin Ebony), Black-English, and the title of this post AAVE(African American Vernacular English)
Beginning teachers across the United States, who have a College BS degree in another field, take a 21 to 27 hour alternative licensure(route) graduate program to prepare them for their new profession. One of the required 3 hour courses is Special Education where the students become familiar with the law as it relates to kids with disabilities and learning disorders.
Chaper nine, in a book by Marilyn Friend, titled Students with Speech and Language Disorders stresses that dialects like AAVE are differences and NOT disorders that need to be fixed or corrected. Similarly, the hearing impaired group Deaf culture has mores and tenets that advance its own rich history, traditions, presence in the performing arts, etc.
Speakers of AAVE believe in functional expressive language liberated from the pedantic rules of grammar set by old white men who were trying to establish norms of speech that would make white people seem superior. They see no need to conjugate the verb to be. I be, You be, He she it be, We be, They be. What is wrong with saying dis in lieu of this? NOTHING, unless you are applying for a job at company run by white folks.