Any small facinating nipple-like object that you can enjoy, play with, fondle or adjust, and get personal satisfaction.
The nu-nu doinkers in the hot tub were spraying out hot and pulsating water. -OR- The television signal was not too good so after I twiddled several nu-nu doinkers the reception was perfect.
An empty-headed (and often shallow) person, especially a female. An airhead. Derived from the sound that an empty missle battery made in the '80s Atari arcade game, Missle Command ("doink", "doink", "doink").