I ran across this old slang expression in an old sailor-poet poem that I've just posted titled "Old Limejuicer." Here's how it appears in context:

Her skipper was a Blue Nose,
Her mate a Portygee; her second was a monkey on a stick; her boatswain me!

Now when I've checked this phrase out on Goggle I found several radically different definitions:

- something to do with a jocky riding with very short stirrups

- something to do with Thai food

- something to do with sexual intercourse

None of which seems to apply to a derogatory reference to a second mate on a tall-ship around the end of the 19th century.

So once again I invite the scholars here to expose their erudite knowledge.

Cheerily,
Charley Noble