Cecil reviews the long history of prisoners having escape-facilitating objects smuggled into prisons here. Simpsons fans may well remember when inanimate carbon rods were celebrated as heroes and model employees, so it’s a little sobering to see what can happen when they turn to crime.
Using welding electrodes and equipment would not permit someone to cut metal. For that, you’d need an Oxyacetylene torch, something that would be hard to smuggle in to prison (especially the tanks!).
I used to have a carbon-arc torch that would melt through all kinds of stuff. Two carbon rods, no gas. It was sloppy but I could see it being used to get through. I miss that thing.
Smuggling a file into prison inside a cake would be difficult. Everything going into prison is x-rayed and a file inside a cake would be pretty obvious. So a tip to all you smugglers: sneak the file in another way and save the cake for non-metallic contraband.
I could give better information on ways that do work but I’ll pass.
Smuggled into prisons is often anger and resentment which then leads to a rapidly proliferating and extremizing criminal culture, due largely to the oppressive war on drugs, that then escapes from the prison and contaminates and destabilizes the larger culture, prompting more extreme legal oppression and paramilitarized police, producing more criminals, and more extremization, which then escapes back into the larger culture.
That probably sounded better when you were composing it in your head, didn’t it?
Note that all of Cecil’s examples were from the days before x-rays. Most examples were from the first decade of the 1900s or earlier, one from 1934. What would work TODAY is not what worked back then, whence the joke originated.
I just want to add that it was a great article–funny, informative, off-beat, and not something I could easily look up on Wiki.
One prison upcountry here in Thailand caught a new inmate smuggling in a couple of cellphones while he was being processed. What gave him away, you ask? The guards heard a phone ringing.
Geez, I hope they hadn’t seen The Dark Knight.
Which I haven’t, so explain yourself, denizen of the comic book obsessed underclass.
I’ll pass that on, to be sure Cecil sees it. That is, of course, the goal of most of Cecil’s columns. Thanks for the praise.
Heh. Spoilered:
One of the Joker’s henchmen was arrested and thrown into a holding cell. Later, we see that he has a cell phone sewed into his abdomen, and when the Joker calls that number it triggers an explosion in the police station.
I left out the best part. Just to make it clear in case some did not think of it: He was smuggling them in in his rectum, so his ass was ringing. 
The address for the image is messed up again. It’s
http://www.straightdope.com/images/art/2013\dope_131018_fileincake.gif
when it should be
http://www.straightdope.com/images/art/2013/dope_131018_fileincake.gif
Some browsers don’t “fix” backslash to slash in URLs automatically.
Guard: “We think you’re smuggling cell phones into the prison!”
Prisoner: “Smuggled cell phones, my ass!”
{RING, RING}
Prisoner: “Mom, I told you never to call me at this number!”
Mom: “WHAT? IT SOUNDS LIKE I’M IN A TUNNEL.”