The plural of banjo is banjos.
The plural of banjo is banjoes. This spelling of the word goes back to the 1820s, now and days, people will accept it without the 'e' but to stick with banjo playing and historical tradition, the 'e'...
banjoes
Banjoes
Here are some: "BANJO BEGS FOR PLENTY OF EGGS" "LOTS OF GOES WITH MANY BANJOS" "AN ENERGY BAR TO GET YOU FAR".