Green’s Dictionary of Slang

(S.Afr.) overly friendly, using flattery with an ulterior motive, sycophantic; also used as v., to become intimate, to share secrets.

1956		D. Jacobson Dance in the Sun 73: Frank found that he and the other were boetie-boetie again, confidential.
2006		C. Miller Salt and Honey 41 : Don’t think I haven’t noticed you boetie-boetie my Pa.