RAZOR BLADES. O Gillette, why would anybody need five blades with only either one chin or two legs?
In theory each additional blade shaves the tiny bit of the whisker that the one before it missed. Presumably this means that the more blades you add, the smaller the remaining bit trimmed by the last one... a literal case of cutting it fine.
Michael McIntyre once did a bit on Mock the Week on Gillette ending with "For that closest ever shave. In fact, this one's too close. It'll cut off your face like a potato peeler. Buy the previous Gillette razor, we couldn't get it any closer than that."
That said, there tends to be a noticeable difference between, say, a three-blade and five-blade razor. When you've got five-minutes before you have to catch a bus to work, and your face looks like cactus, those five-blades are a godsend. A quick once-over tends to do a passably thorough job, though you might want to bring along the aftershave with you on the commute.
A long time ago, Saturday Night Live, in response to the 'two blade razors' showed a three-blade razor parody commercial. The fake ad looked completely real until the final line: "Because ... you'll believe anything!"
Later, they did another commercial parody about "The Platinum Mach 14" — A razor with 14 blades.
One-upped by a real razor ad. The 15-bladed Quintippio is a parody, the actual product is an electric razor.
Mad TV one-upped SNL and did a skit with the fiction Spishak Mach 20 which had 20 blades and shaved the man to the bone. Watch it here.
The Onion did a parody article called Fuck Everything, We're Doing Five Blades shortly after Schick introduced their four blade razor in response to the popular Mach3. This is made extra hilarious by the fact that this is what Gillette actually did a few years later. And they added one more on the back.
Rotoshaver - an actual (electric) razor with 9 blades.
The Daily Show spoofed the Razor Wars in an interview segment with the commentator's own 16-blade razor...it included four four-blade razors connected at the handles to a rotating motor. The skit ended with the commentator leaning his face in towards the spinning razors...
The Economist published this graph◊ estimating the rate razor blade technology's increase into the future. We will soon have razors with infinite blades.