I was lent a shotgun once, upon the owner's insistence.
Deer season @ a cousin's spread. I'd brought an 870 synthetic upon which I'd mounted a rifled barrel w/ a cantilever and Bushnell Banner SG scope.
My cousin (whose taste in firearms is extensive and exemplary BTW) told me to put it away and handed me a GORGEOUS old 1100 set up for deer w/ a Leupold scope mounted on it.
It was my first time in a treestand. It was also about 3 degrees that morning. I was so paranoid about making sure that my cousin got the 1100 back in AT LEAST as good a condition as it was when he handed it to me, that the only thing I could think to do was take off my coveralls and wrap the gun in them before I tied the tumpline to the parcel and pulled it up into the treestand after I'd gotten up there.
COLD!!!!!
Did I mention COLD!!!!!?????
Did I also mention that I don't do heights?
I don't know what had me squirrellier, bein' up there in the ether half frozen to death and tied to a tree, or picturing that 1100 fallin' off my lap and plummeting earthward. Deciding that I'd rather be the one doing the falling than the 1100, and that even if it DID work out that way, it would still be devoid of any kind of "fun factor", I rejoined the ranks of the ground hunters.
I've also lent one, sort of.
A very dear friend, a type of guy a man only ever meets one or two of in a lifetime (and a forum member, actually), had sent his home defense pistol out for some work and asked to borrow a shotgun to replace his pistol in that role. "Certainly!" So I took him an 870 w/ a 20" cylinder bore and a box of ammo.
Funny how ways can show up out of the blue that you married the right woman. I was in my favorite chair thinking about my bud and the shotgun a couple days later and realized I should have just given it to him. Right then, my wife looks at me and says, "You know, ya oughtta just go to Greg's house and put a red bow on the buttstock of that 870."
There's always been a deep sense of sacred nobility and honor in connection with the presentation of a firearm to a gentleman as an indication of your respect and opinion of him as a friend. In my world, it's the highest honor a friend can bestow. I've been in the incredibly fortunate position of having been a recipient a couple of times, along with having been the presenter, and the gravity of each instance was not lost to me in the very least.
Beyond the 2 above instances, I've neither lent nor asked. Everybody I know is either enough of an enthusiast to already have what they need or doesn't want any part of a "nasty ol' gun".
There've been many gentlemanly experiences shooting what each other brought to the range, however.
Sorry for the diatribe.