Favorite "fun gun." Fun thing about answering these fun threads is that you can make whatever you want of it. All of my shooters are fun... my 10-inch barreled T/C Contender in .44 Mag with heavy handloads is probably the least fun, because it's horribly light and recoil is just plain not enjoyable with it.
But for this thread, I'll define a "fun gun" as one that really just don't fit any other role, or it doesn't fit them well at all. But it has FUN nailed.
I've got a perfect gun in a perfect caliber for that role -- all fun, and no real purpose: Ruger Blackhawk, caliber .30 M1 Carbine.
It's got the only barrel length they've ever offered in this caliber, 7.5 inches, to get something closer to a full burn out of a made-for-rifle caliber.
With a 7.5 inch barrel, a huge & heavy revolver with extra metal to spare at every corner, throwing 110 grain pills and running 40,000 psi, this SOB does everything in the world you want that defines "fun."
It's loud as all hell. Maybe that's not really fun, but it turns heads. Ask around this forum for folks that have shot one, everyone says, "loudest damn handgun I ever heard." The muzzle blast, flash & fireball is the textbook definition of fun. That nuclear fireball turns heads at the range, too. People want to know what on earth is dropping these bombs. Recoil-- it's almost not there. Take a big, heavy hunk of metal and send light baby bullets out of it and recoil fails to show up. It's hilarious.
And it's accurate. The bullets are cruising pretty quickly, so it shoots flat and still hits at ranges where big bore rounds fall in to the dirt from handguns.
What's not fun about it? Well, there's some things... Reloading for it is not as fun as other calibers because you have to be completely on top of measuring and trimming for case length. Too long and they won't chamber. Too short and you won't get proper primer strikes. Also, hot ammo tends to make the cases stick in the chambers horribly.
Because it's so large, it's almost unwieldy. Barrel is long, gun is heavy. It's not a good caliber for anything other than plinking, pretty much.
Also, this isn't a finely blued handgun. It's a brand new Ruger, so there's no beautiful deep bluing. It's more like black, and lots of it. I think some mother of pearl (or fake pearl) grips would look better than the black plastic original grips.
You want a heap of fun, making people ask questions, and turn their head to see what you are shooting? This one will do that. But beyond fun, it doesn't do a lot.