Thiefs Knot

A while back, Theifs could be detected by fake square knot ties, the usefulness for this knot is also getting out of it, since the rope easily slips from the other one. So when your freind ties your hands behind your back, this is the knot to use.

Step 1: Materials Needed

perferably you want two ropes, but it can be done with one rope.

Step 2: Loop Holes

make two loops

Step 3: Under

put one loop under the other loop

Step 4: Over the Loop

now you take the ends of the loop that is under the other loop, and take the ends and put it over the other rope.

Step 5: You May Now Slide the Rope

notice that, the rope easily slides, but looks like a square knot, good for magic

Comments

[thing 2]

This looks quite like a Cow Hitch on another rope. Hmmm, looks good though. :)

[rmoonie]

Larkshead and cow hitch (or bull hitch) are the same, a hitch tied around a solid object like a ring or post. When the tail or running end is secured, it is referred to as a girth hitch.
In the above picture the bulk of the knot has been slipped over, appearing to be a hitch, although it is not (not pun intended). Knots are tied with rope, hitches are rope tied around another object.
The picture above may have been a square or reef knot beforehand, or even a thief's knot, but one can not identify it without seeing the free or running ends of both ropes. On a Reef knot they are on the same side, on a thief's knot, they are opposite, as an identifier of tampering, eg: theft from contents within a tied package.

My background: 15 years in Scouting, 18 years as a Production Rigger, 21 years rock climbing.

[FenrisLokison]

Spot on mate, The other inaccuracy is that thieves used this knot to tie one another up in order to release themselves ( Presumably in the presence of an arresting officer/person). You would have to pretty dumb to get 1 person to tie another up ( presumably under duress ), tie them up and not check ALL the fastenings.

In Australia the British did exactly as you say. As most transportees ( at the time pretty much legalized slaves ) had free run of the colony, their Gaolers used to tie the stockpiled bags of grain etc with a thief knot. If when inspected the knot turned out to be a reef knot they knew a thief had indeed been at the goods. That's when the witch hunt began as the thief had nowhere to go.

Historically this is extensively well documented.

Good on ya for spotting it mate.

[Morgoroth]

I have always heard of something different for the thieves knot. It has the lead ends coming out of two different sides of the rope. This is a larks head tied onto a rope.

[wobbler]

It's knot. It is you know.

[shrpshtr325]

also, im not sure how well you know nots, but having been in the boyscouts for11+ years and being an eagle scout, that does not look like a square knot to me, maybe to an inexperienced person, but not someone who has a clue

[SumGie]

Actually, if you took a properly tied square (aka reef) knot tied with the blue and white cords this person has used, and pull both of the blue ends, what you end up with looks exactly like step four. 
This shows the easiest way to untie a square knot.  Pull both ends of one side, until that side is straight, and then you can pull it out of the other side, which has transformed into another kind of knot entirely.  I think It's called a cow hitch or some such.

[hacker006]

yeah, I don't know knots really well, but from a distance it supposedly can be mistaken as. However, I do apperciate you pointing out your intellect on the matter

[dchall8]

A true thief knot does look like a square knot.  You were sorta close. 

http://en.wikipedia.org/wiki/Thief_knot

[SWV1787]

when placed over a rod or firm device the white rope's knot is called a "larkshead"

[microman171]

This knot is also called the cow hitch.

http://en.wikipedia.org/wiki/Cow_hitch