To transform wire hangers into hooks, you need wire hangers, wire cutters and pliers.
Unwind the neck of the hanger. The original hook of the hanger serves as stake #1. Cut around the hanger. I was able to get two stakes at the neck, one at each of the corners, and then one straight piece along the bottom (shown here with a bend already).
For the one straight section from the long bottom of the hanger, you'll need to add a bend using pliers starting around 2/3 to 4/5 of the way down the straight part.
Stick the stakes into the ground to keep your irrigation tubing in place.
You can use them all over the garden. When I went to take pics of these today, I see that the one that had some kind of yellow-greenish coating (left, on the white tubing) is doing much better in the elements than the one without (the one on the right holding down the black hose is rusting).