Each xkcd comic has hidden title text.
Hover your cursor over the comic to see it.
The title text of xkcd 308
suggests making a climbing harness
out of Ethernet cable.
Whether or not this would work
is a subject of some debate.
I decided to find out myself:
Would Ethernet cable work well for climbing? by holding myself from a car lift 
Click on any picture
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The knot slipped because Ethernet cable is smooth
and it is too stiff to tie tightly.
It was also hard to hold on to.
Tightening the knot
caused the cable to snap
when I tried to hang from it.
The cable broke where it wrapped around the car lift.
The rounded edge was digging in to the cable.
Now each half of the cable
only held half of my weight.
The cable broke in both places
where it wrapped around the lift.
To be able to make a clove hitch,
the short fibers should reach three times
around what you are tying the rope to.
Twist one short fiber around one end of the long fiber.
In the same direction, twist two short fibers together.
These are your yarns.
In the opposite direction,
twist the short yarn
around the the long yarn.
Twisting in opposite directions
makes the twists oppose each other,
so that the rope does not untwist.
You have now made rope
on one end of the long fiber.
Repeat on the other end.
When I braided both ends into rope,
the cable did not break at the knots.
The one long fiber of Ethernet cable
was able to hold my weight,
even when I bounced a little.
However, Ethernet cable breaks easily
when wrapped or tied. 
No, Ethernet cable would not work well for climbing,
although it does have the strength to hold a person.
 In retrospect, this is not exactly what xkcd 308 proposes. In the future I will make a climbing harness.
 The car lift was just a convenient anchor to suspend myself from.
 The clove hitch only bends the cable around what you are tying it to, not around the cable itself.
 I regret not taking late-night pictures of the final parts of the experiment.
 I suspect that when the cable is bent, it flattens, and one wire rips at a time.