When three people are walking, the dunkus is the one who walks behind the two people standing side by side. Defined in a twitter thread by twitter user @KylePlantEmoji in a thread created to define words that other users had made up.

A term used to reference cannabis/marijuana/weed.

a male's private part (s)

In a Group of three the one walking behind the two pair.

Someone who's an all-out goofball