This is a really easy project, but definitely worth practicing a few times before trying this on your favorite jeans.
Step 1: Materials
1 pair dark jeans
2 rubber bands
1 large bowl or other liquid container
1 bottle bleach
1 measuring cup
Step 2: "Crush" your jeans
Then use the rubberbands to keep it in a ball shape.
Place the jeans in the bucket.
Step 3: Mix Bleach
Mix 1 part bleach and 4 parts water in the bowl before you put it in the bucket (this is probably unnecessary).
Then pour over the jeans into the bucket. Add enough bleach/water mixture to cover the jeans. I ended up using about 5 cups of bleach.
Step 4: Wait and Observe
I checked on them by moving the rubberbands or pulling them apart a bit to see if there are signs of color change.
Different jeans, take different amounts of time. I tried 3 different types of jeans before these, and had pretty diverse results.