Seriously. Why do people do this? A new, extra-long, in-the-wall smartphone charger is, on average, just $6-7 on eBay, so there's little reason to not have one (I have at least two - one downstairs at the table I eat and write at, the other beside my bed).
Extension cords are not the way to go (says the person who keeps her modem halfway up a full flight of stairs to spread the signal more evenly. There are no outlets on the staircase so the modem runs off an extension cord, which probably also degrades its performance. We should mount it on the ceiling at the midway point of the first floor. I'm not sure why we don't).
As far as I know the modem's the only thing we're foolish enough to run off an extension cord (a brown one, too - just read an article last week saying we need to throw out brown extension cords).
But it's like: I have a huge plastic storage container the size of the floor of my closet, that sits on the floor of my closet, a closet already overstuffed with All The Things. Besides computer and phone hardware and peripherals it's got all these cords - coax, Ethernet, stereo cords, telephone line, TV cords, power supplies, power strips, surge protectors, extension cords - so it's a mammoth pain in the ass to pull out, dig through, and find this safer extension cord I just found out I need.
Not to mention I don't think we have one, which makes me continue to put off trying to find it. But until I know we don't have one I refuse to buy one, either, so...this is purely "do as I say, not as I do"...brown extension cords? Probably you should just chuck 'em.
ETA, 4-4-2017; darkoshi explains: "It's not the color of the extension cord that matters - there are both white and brown ones commonly for sale nowadays, and the only difference in those is the color, so one isn't better than the other. But if you have a very old style, which as the articles also mention, has relatively thin wires, or non-polarized plugs, or if any of the coating is worn off, then it would be good to replace it. I guess the older ones must have mainly been brown."
Very good to know!