three packets short of a fun dip

Expression used to insult someone's intelligence or personality.

Fun Dip is a candy found in US/Canada. It is unique in the fact that it requires two separate candies to be combined in order to properly enjoy it's intended mode of consumption. First, a tasteless sugar stick must be licked, then it must be dipped into one of three included packets of flavored sugar powder. If you remove the three packets, you are left with the tasteless sugar sticks, making the product incomplete, worthless, and bland. Therefore, describing someone as 'three packets short of a Fun Dip' means they are (a) missing general intelligence or (b) lacking flavor (in the personal sense).

I would never vote for (POLITICIAN)! That (GENDER IDENTITY) is three packets short of a Fun Dip!