soixante-neuf
Concise Oxford English Dictionary © 2008 Oxford University Press:
soixante-neuf /ˌswasɒntˈnəːf/
▶noun informal sexual activity between two people involving mutual oral stimulation of the genitals.
– origin Fr., lit. ‘sixty-nine’, from the position of the couple.
'soixante-neuf' also found in these Oxford entries:

