Is what you say, when you and at least one other person, simultaneously, say the same word(s). If you are first to say jinks, you are in effect the jinks master, and the person who uttered the same word(s) and who is now jinksed, cannot speak, until someone says their name in full. Utterring words while jinksed however, will result in double jinks, triple jinks and so on and so forth, for each additional word spoken.
Trudy and Rebecca: The chocolate one please
Trudy: double jinks!
Cecile: Rebecca Smith
Rebecca: Phewww, thanks cecile