Like a wingman, but for a guitar player. When you pop a string at a gig, & grab your backup guitar (or someone else's guitar) to keep going, this is the dude that replaces the string for you with lightning speed.
I popped the high E on the 2nd song, but luckily Jim-Bob the guitar player for Ellen and the Degenerates was there as my stringman and I had it back by the time we played "Hey Joe".
A really crappy guitar, eg. a turd.
I tool the guiturd to a tech so he could proverbially polish it with a setup.
A polygamist has many wives, a polyguitarist has many guitars.
I have some serious GAS, so I've settled into being a polyguitarist.