This one reminds me of middle school when all the Cool Alt Kids would rip intentional holes in their jeans and string safety pins through them. Still, this is a great punky look. Youtube tutorial here.
Have a small scrap of Halloween fabric left over from another DIY (or need an excuse to buy pretty fabric like the ones on my Dark Fabric Pinterest Board)? Here's how to patch denim using whatever fabric you prefer: Tutorial here.
For a variation on a fabric patch, why not cover the hole with a scrap of fish net? Again, in a contrasting color this would work wonderfully. If you wanted something even more deathrock, use safety pins to keep the net in place. Similar to this.
For something a little cuter on less fancy jeans, how about a monster face? Using the hole as the mouth, arrange felt eyes and teeth in a monster shape and stitch in place. Tutorial here.
How do you patch your torn denim? Or do you just get a new pair?