Don't do it.
My drummer sometimes does one off gigs with another bass player and guitar player, which I have no problem with (I know both guys, we're not really friends, but I know them). A couple of years ago, they were doing one of these shows and his bass player needed a cab. My drummer asked me if this guy could borrow one of my spare cabs. I said no problem, but it's at a friends place several miles outside of the city—I jam with this friend of mine on occasion, and also taught his son how to play bass, so I left my spare rig there for the jams and for his son to use on a long term basis. I said that he had to arrange with my buddy to pick the cab up, and to return it when he was finished with it. This triggered a series of telephone calls with my drummer and his bass player trying to convince me to deliver the cab. Each call ended with me saying no. You want it, you go and get it (this should have been a red flag). They finally manage to work something out to pick up the cab themselves.
The gig is done. About a week later, I get a call from my buddy asking me if I'm going to bring the cab back for his son to use. I said, ahhhh, the guy didn't return it yet? Nope. So I get on the phone to my drummer and ask him why the cab hasn't been returned. I'm informed that his bass player has it at his house, and he's waiting for me to come and pick it up. I say, uh, no, that wasn't the deal, you guys were supposed to return it to the same place that you picked it up from soon after the gig. He tells me he's going to call the bass player. This telephone game goes on for a couple of weeks... at some point I call my drummer to ask him what the hell's going on, and he tells me that his bassist had another friend pick the cab up a few days before, and he was supposed to deliver it, so as far as the bass player is concerned the matter is out of his hands. I flip. I have no idea who this other person is or where he lives, and he's had my cab at his place for about a week. At some point, I realized that if I din't go and get the cab, I was never going to see it again. It took me a while to squeeze this stranger's address out of my drummer through his bass player. So I head over to the stranger's apartment... the door's open and my cab is sitting right there in plain view of anyone passing by... I ring the doorbell... no response... I bang on the door... no response... so I walk in... the place is a mess, the guy's a drug dealer and he's completely zonked on his couch... either in a deep sleep or a drug induced coma!! So I just picked up my cab, left the door open, and split—and took it back to my buddy's place.
I was livid! I called my drummer and blew his face in, which he in turn passed along to his bass player—to no avail—the guy just didn't give a crap.
About six months later, guess what? Yup. I get a call asking if the same guy can borrow my cab again!! I can't really print what my response was here, but use your imagination, and insert as many swear words as you can come up with... you'll probably be pretty close.
So, uh, yeah. Don't do it.