I thought for the last 50 years or so it meant ‘dumb sh!t’ or variations thereof.
It does mean dumbass or “prick” or “coward” etc in the vernacular depending where used and how.
But the insult is derived from a word literally meaning a hanging pubic hair.
This was explained to me 3 decades ago by a 2nd generation Cuban now living in Miami who’s dad was the Spanish ambassador to Havana before it fell and who used words like “cono” and “carajo” in every utterance
Cubans curse like Australians