Tefsen played her biggest television role between 1980 and 1993 as housekeeper Mien Dobbelsteen in the VARA comedy "Zeg 'ns Aaa". Although not initially intended, the series revolves around the housekeeper Mien and her husband Koos, rather than the female, single general practitioner with two children. Every week, a millions-strong audience heard Mien answer the phone with the famous "This is Doctor Van der Plóóóééégg's assistant!!" Tefsen did not audition for the role. Director Nico Knapper knew her from another series and saw in her the ideal Mien.
