How to make a Slipknot for Crochet

Hold the yarn with the tail end in your right hand.

(Leave enough tail to sew in later)

Make a loop by taking your left index finger under the yarn...

...then holding the loop in place with your left thumb 

(make sure the tail end of the yarn is on the bottom) 

 Insert your hook through the loop.

 Yarn over.

(Wrap the ball end of the yarn over the hook)

 Pull the yarn through the loop.

 Tighten the knot.

Voila!
You made The Crochet Slipknot!