A creative fighting tactic used 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 broken 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).
Anywhere in your own home - cameras (those flash bulbs are always a handy distraction), the couch, pet cages (especially if Fido or Fluffy is inside), the indoor fireplace (HOT HOT HOOOOT!!!), or towels, blankets, and curtains.
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.
Somewhat overlaps with environmental kills in Diamond's Cut, as 007 kills two final villains with sticks lying around: the armsí dealer gets throttled with a fallen tree limb, while final villain gets [[Squick stabbed through the stomach with a branch]].
Also, the chase scene at the supermarket earlier. The second armsí dealer is running away and Bond would need a car to catch up, but he doesnít 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 Doctor Steel's song, "Lament for a Toy Factory", Steel goes insane after being fired by a toy factory. He invades the factory with an army of toys and gasoline-filled Super Soakers.
In Kevin "Bloody" Wilson's song about The Front Bar Featherbrain Non-Title Fight, a pool cue, broken off pool table legs and a toilet are all employed.
Myths & Religion
In The Bible Cain picked up a rock and killed Abel with it, and Samson killed an army with a donkey's jawbone.
Swords <-> Ploughshares
Shamgar's act of killing six hundred heavily armed spearmen with an oxgoad (stick with a nail in it). (That would be Judges 3:31, if you've never heard of him.)
Although not exactly a weapon in the usual sense, during a period of righteous fury, Jesus cleared out the temple in Jerusalem with a whip made out of belts.
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.