The Jargon File (version 4.4.7, 29 Dec 2003):

boink
 /boynk/

    1. [Usenet: variously ascribed to the TV series Cheers, Moonlighting, and
    Soap]v. To have sex with; compare bounce, sense 2. (This is mainstream
    slang.) In Commonwealth hackish the variant ?bonk? is more common.

    2. n. After the original Peter Korn ?Boinkon? Usenet parties, used for
    almost any net social gathering, e.g., Miniboink, a small boink held by
    Nancy Gillett in 1988; Minniboink, a Boinkcon in Minnesota in 1989;
    Humpdayboinks, Wednesday get-togethers held in the San Francisco Bay Area.
    Compare @-party.

    3. Var of bonk; see bonk/oif.


The Free On-line Dictionary of Computing (30 December 2018):

boink

   /boynk/ [Usenet: variously ascribed to the TV series
   "Cheers" "Moonlighting", and "Soap"] 1. To have sex with;
   compare bounce. (This is mainstream slang.) In Commonwealth
   hackish the variant "bonk" is more common.

   2. After the original Peter Korn "Boinkon" Usenet parties,
   used for almost any net social gathering, e.g. Miniboink, a
   small boink held by Nancy Gillett in 1988; Minniboink, a
   Boinkcon in Minnesota in 1989; Humpdayboinks, Wednesday
   get-togethers held in the San Francisco Bay Area.

   Compare @-party.

   3. Variant of "bonk"; see bonk/oif.

   [Jargon File]