They first learned how to speak fluently in Swahili, however as the days go by, the Whites seem to be interested in knowing more than just our National language. They have gone to an extent of learning some of the native languages which they use to express themselves when conversing.
Speaking of which, I came across a video clip of a mzungu guy whose Kikuyu know-how is not a matter of guess work. In the clip, the unnamed man can be heard talking fluent Kikuyu while in a serious conversation with a woman from the Central province.
What more can I say! Just watch the clip and hear for yourself.