sixty-nine definition by Webster's New World
Webster's New World College Dictionary Copyright © 2010 by Wiley Publishing, Inc., Cleveland, Ohio. Used by arrangement with John Wiley & Sons, Inc.
Slang a sexual activity involving two individuals and consisting of simultaneous oral stimulation of the genitals: somewhat vulgar
often written 69
sixty-nine definition by American Heritage Dictionary
noun Vulgar Slang
Oral-genital sex between two people at the same time.
Origin: From the resemblance of the figure 69 to the position assumed by the two people.