5. One Dollar
Back when Bruce Wayne was just starting out as Batman, he was kind of an arrogant prick. He even bet Alfred one whole dollar that he couldn't name Batman's weakness. Naturally, Alfred took this as a challenge. The dutiful butler hired some goons to re-stage a mugging that looked eerily like the Wayne family murder, and placed them in an alley for a few hours. When Batman finally found the set-up scene, the fake Thomas and Martha Wayne caught him by surprise and beat the shit out of him. That's when Alfred walked out of the shadows.
So, the butler proves his point (dead parents are considered weaknesses, duh), Alfred takes his dollar and Batman learns a valuable lesson.
But wait, why does Batman have a dollar in his utility belt? It looks like it takes up the whole pouch -- does he consider it a gadget? What does he use it for? Is there some kind of crimefighting breakroom with a functioning vending machine? Then again, if Alfred went to the trouble of rigging up this trap for Bruce, maybe he was the one who slipped the dollar into the utility belt just so he could make a dramatic gesture later on. So, our options are A) Batman keeps petty cash in his belt in case he craves Bugles on the job, or B) Alfred is the real Batman.
We've already detailed the embarrassing exploits of a broken Batman that lead up to this gadget, but here's the CliffsNotes version: While Bruce Wayne was recovering from an appointment with self-styled chiropractor Bane, a pony-tailed dweeb named Jean-Paul Valley took over as the new Dark Knight, wearing a souped-up Batsuit that looked like a cross between a Power Rangers Megazord, The Fresh Prince of Bel-Air and 20 Other Things That Only 90s Kids Will Get. After defeating Bane, J-P went on to make further "improvements" to the suit, including a shuriken-launcher, a red thing above his eye and seriously a SHURIKEN LAUNCHER. Because that wasn't enough, he built in a god damned flamethrower.
Jean-Paul was going nanners, as it were, and became obsessed with the "cleansing flame" provided by a MacGuyvered BIC lighter and a shit-ton of lighter fluid. This was an affront to Bruce Wayne, who objected to the barbaric weapon, famously coining the phrase "This is not 'Nam, there are rules." The Batmen fought and you can probably guess which one came out the victor. You might be able to spin this as Classic Batman taking on the muscle-bound pouch that was superhero comics in the 1990s, but on some level DC really was trying to push a new edgy Batman that was so badass that he would revel in lighting his enemies on fire. It's more overkill than getting an Excessive Overkill in Unreal Tournament while listening to 80s thrash metal band Overkill.
And really, come on. Classic Batman would never do something as stupid as attaching combustibles to his limbs.
Batman has a ton of vehicles at his disposal, like the Batpod, Batplane and others, each sold separately?. So it's more than a little suspect when Robin asks Batman if, instead of using one of their many modes of transportation, they could instead crazy-glue a couple firecrackers to some stolen shoe rentals from Skate Palace. Look at it this way: A Batmobile seats two and has airbags and has lots of gadgets, the Batplane has the power of fucking flight and the Batboat has domain over any canals, inlets and fjords you can throw at it. All of those would be sound alternatives to going slightly faster than a waitress at a drive-up fast-food restaurant.