I need the least secure knot you got

[SirCantaloupe]

Well, the whole ball bearing deal never worked out. I couldn't find cordage that would form a secure (no gaps) monkey's fist or Turk's head on the ball bearing.

On the other hand, I've found a slipped buntline to be the perfect knot for hanging my camping hammock up, and for the tiedown stakes. Secure, easy to tie, easy to untie - lovely all around. Thanks for all the help, everyone!

[Transminator]

How about the HFP Slippery 8 Loop?

http://notableknotindex.webs.com/slippery8.html

It is quite stable for uni-directional pull and if you want to release the object, simply get it into the adjustable mode and pull the end through.
Additional though: instead of threading the end through the figure 8 when tying it, use a bight and you have a slipped version of the HFP which you can still open, even if the knot has tightend quite a bit.

I just tried it with a piece of string and a ring and it worked perfectly.
Would that be a candidate?

P.S. this slipped version of the HFP is also suitable as a tensioner, as it can be released easily, even when pulled tight around the object.

[nkuzmik]

I'm a bit unclear on something.  Do you want the knot to release when it is snagged, or do you to be able to simply reach down, grab your keys, give them a yank and have them come away?

[stebold]

I just braided a bootlace and I like it so much I want to wear around it my neck for awhile, until I get bored of it. (I still find the braid knot from a single cord to be a miraculous thing!)  Like you, I want it to come apart with with a sharp tug because it's just not wise to wear something around your neck that has a breaking strength of over 300 pounds.  My solution was to make two nooses - just simple overhand nooses to keep the knot size small.  The end of one noose is inserted into the other noose and tightened down. With just the tip end of one noose clinched by the other the necklace comes apart with a satisfying sharp tug.  Perfect!
For something like a knife hanging from your waist that you don't want to lose you may want to use a positive stop for extra security - perhaps a short (1/2" - 1") length of cord with a stop knot on one end which goes through the clinched noose end.  When you want your knife, you pull out the security cord and then yank the line off.

Unfortunately, I can't post pics of my necklace at this time.