'Baas' is an Afrikaans word that translates as 'master'. It is/was usually used by black unskilled laborers to address their white bosses and has become widely symbolic of the racial oppression that characterized the apartheid regime.
Add: Anecdotes - Unfortunately, the myth of white superiority has not only been ingrained in the minds of many white South Africans but also black South Africans. I remember as a child our family employed a domestic worker (most middle class families, especially white families in South Africa have maids who come in at least a few times a week - and usually are employed full-time. Gardeners are also common, but usually have a couple of regular clients - they may work for one household two days a week, and work the other two at a different household, and then the last day of the week at another household). At any rate, our domestic worker used to refer to my father as 'baas', even though he asked her to rather call him by his first-name or Mr. (surname). a number of times. She didn't seem to be able to bring herself to do it, it almost came instantly to her, such was the ingrained sense of devaluing herself. For E.G:(names obviously changed here)
My dad: "Please can you call me Dave?"
Alice: "Yes baas."
My Dad: "Or Mr. Smith?"
Alice: "Yes Mr. Smith, baas."
You have to remember that, under the apartheid era, many black people who did not refer to to their 'employers' as baas faced physical violence or worse, and had little if any recourse to justice. Fortunately the use of the word is dying out, but it is taking a long time and we still have quite a long way to go.
It is hard to think of an anecdote, insofar as this connotes an unusual or special incident, which is not the case in S.A. I am not sure where you are from, but it would be like me saying to you, "can you tell me an anecdote of someone crossing the road." Probably nothing would stand out in your mind, because you see it all the time.
Another word in South African lingo is a "baaskap mentality", which refers an ideology which perpetuates the belief that whites are superior to blacks and that blacks are their natural servants. This word brings an anecdote to mind. - In the recent elections, leader of the now defunct Independent Democrats, Patrica de Lille, accused Helen Zille the leader of another (and larger) opposition party (The Democratic Alliance) of having a "baasskap mentality". The parties have since merged (after the 2009 national elections when the comments were made), which should indicate to you how crazy politics in S.A. is.