A creative fighting tactic useful by unarmed people in any situation: Make what's around you a weapon. Even outside the dangerous environments, there's a lot of stuff to try. Anything can be used as a club if it's sturdy enough, and most stuff will develop a sharp edge if properly coaxed. For comedy value, go as wacky as you like.
Depending on the setting, there's a lot of options:
Prison - Real knives are hard to get and quickly confiscated. So convicts improvise a lot. All of the above is used, with the addition of mirror glass, plastic bags, elastic bands, gum, toothbrushes, and many, many other things. Notably, ingenious inmates have been known to make usable shivs out of papier-mache toilet paper (you can literally flush the evidence), a shotgun out of bedposts (which was used to blow out a pane of bulletproof glass before they held a guard hostage), and best of all, a fully functioning crossbow (the components included rubber gloves, a wire coathanger, and ten toothbrushes).
At the store — Fresh produce, pop caps, anything in a can, cash registers, depending on the store TVs, furniture, VCRs, heavy electronics, candy balls, toys.
Car Fu. Slow or fast, as long as it's undodgeable, it's quite dangerous.
Anywhere in your own home - cameras (those flash bulbs are always a handy distraction), the couch, the golf caddy, pet cages (especially if Fido or Fluffy is inside), the indoor fireplace (HOT HOT HOOOOT!!!), or towels, blankets, and curtains. The flashlight at the garage is also useful both as a blinding light and as a club.
In The Mouse of Konoha, always being prepared this is one of the three shinobi lessons Naruto learns when he starts trading scavenged weaponry for tutelage.
The protagonist of Toy Hammer is an artist with no combat training whatsoever, but when he needs to put out a fire, he subsequently discovers that the extinguisher works as both a bludgeon and (when sprayed) a stunning weapon. He wields it in almost every fight, to the point that it becomes a part of his mental landscape for more than one Battle in the Center of the Mind.
In With Strings Attached, Ringo whacks Grynun over the head with a guitar to prevent her from castrating George.
In The Eye of Argon, Grignr sharpens the pelvic bone of a rat and slashes one of the guards with it during his escape.
Also, the chase scene at the supermarket earlier. The second arms’ dealer is running away and Bond would need a car to catch up, but he doesn’t have one. So what does he do? He picks up a shopping trolley and rides it downwards to catch up while staring directly at the camera as the Bond music is played out loud. This is Played for Laughs taken Up to Eleven.
Terrorists throwing empty boxes at Bond, which he catches and throws back even as they both have guns.
In Forward, during a fight inside an infirmary, Jayne kills an opponent who is strangling him (and wearing low-profile Power Armor) by braining him with a bedpan and cutting his throat with a scalpel. Jayne improvising weapons is something he keeps doing over the course of the story as well; in his flashback to when six men tried to kill him, he ends up taking out one of them by rigging a massive incendiary bomb using gasoline and small explosives. Also, the whole crew ends up improvising an anti-ship missile out of a disused drone, shuttle engines, and a repurposed flight computer.
In Crowns of the Kingdom, the Disney Princesses storm the Matterhorn to rescue their boyfriends armed with sports equipment and kitchen utensils.
In Sonic the Hedgehog fanfic Prison Island Break, Shadow is highly skilled at creating shivs out of anything. Not only that, but he carries multiple shivs at all times, and the guards rarely manage to confisticate them all after a shakedown.
In Broken Saints, Raimi defeats a deranged Kamimura by picking up a mirror off the ground in the alleyway and smashing it over his head.
Tifa in Dead Fantasy. Hold on this might take a while... Ether bottles, bits of lava stuck to her shoes, a table, a garage jack, the same garage jack cut in half, and lastly the chains that where used to try and restrain her.
Volume 2, Episode 1of RWBY had Teams RWBY and JNPR utilize various foodstuffs as analogues for their traditional weapons. Nora uses a watermelon on a pole, Yang uses turkeys as gauntlets, Pyrrha uses a baguette as a spear, Weiss uses a swordfish, and… stop laughing!