What is the musician's slang for their instrument?

Axe - ANY musical instrument.
Ex: Man, - what do you think of my new Axe?


https://www.studyblue.com/notes/note/n/jazz-slang/deck/2998137

You'll find several entrys in the Urban Dictionary for AXE being a musician's instrument...That's probably as good a source as any on this topic.

Originally, an AXE was an electric guitar (as in Jimi Hendrix) and I have heard it used with regards to other instruments.

http://www.urbandictionary.com/define.php?term=axe

There are many different types of musician. Certain ones have distinctive terminologies - like jazz musicians referring to the tenor saxophone as a tenor horn in disregard of the existence of an instrument already known as a tenor horn (found mainly in brass bands) and of the fact that the saxophone is not a horn. Axe is a term only used in pop/rock music. You won't find it in classical, folk or brass and wind band circles at all - to name the three I've had most involvement with. And on the occasions I've appeared with a rock outfit, none of them used the term either. There is no general term used by the majority musicians to refer to an otherwise unspecified instrument. Other than instrument.....

Axe, in popular music, an electric guitar or a wind instrument.


https://en.wikipedia.org/wiki/Axe_%28disambiguation%29


Slang A musical instrument, especially a guitar.

http://www.oxforddictionaries.com/us/definition/english/axe



Or maybe a saxophone

"The use of "axe" as slang for a musical instrument dates back to 1955, i.e., in the edenic pre-Kiss days. The instrument to which "axe" was first applied, however, was not the guitar, but the saxophone. The logic may have been simply the "sax/axe" rhyme, but another theory ties "axe" to the "swing" of a jazz sax player in full stride. "Axe" was also later applied to the trumpet before becoming accepted as slang for the guitar, a use which has probably persisted in part because of the instrument's resemblance to an actual axe."

http://www.word-detective.com/041007C.html

So...I think we can safely say that some people use the term AXE for their guitars, some use the term AXE for a wide range of instruments and some don't use it at all.