Bleaching jeans gives them a splash of personality, and it only takes a few hours. Using the splatter effect on black jeans in particular creates a dramatic effect and gives the pants a lived-in look that makes them as easy to dress down as they are to dress up; you can wear them with virtually anything. And of course, because bleach doesn't fade away, you never have to worry about undergoing the process again -- until you're ready to do your next pair jeans, that is.
Lay down a plastic tarp outside and place your jeans flat on top of them. Doing this inside allows the noxious bleach fumes to build up -- and you risk splattering bleach on a lot more than your wardrobe.
Put on your rubber gloves and safety goggles. Bleach is a powerful chemical, and it can burn your skin and eyes. Even just the fumes can make your eyes sting, so protect them, and wear old work clothes that you don't mind getting ruined, just in case some bleach splashes or spills.
Fill the bleach bottle's cap with liquid bleach if you want big splatters. Hold the cap over the pants and shake it horizontally, so that the bleach splashes out over the sides. When it hits the denim, it starts working immediately -- on black jeans especially, you'll be able to see where it's eating away the color. Splash as much as you want, then flip your jeans and do the backside.
Dip a disposable paint brush in bleach for small splatters -- it may be easier if you fill a paint tray with bleach first. Dip in your paint brush, point it at your jeans and flick the brush through the air, as though you are trying to shake something off its tip. The bleach will splatter onto the jeans Jackson Pollock-style, and you'll see the marks that it makes. When it is splattered to your liking, flip it over and repeat on the backside.
Let the bleach set for an hour or so, then hang dry. Once they are dry, run them through the washer and dryer using detergent as you normally do; this sets the bleach permanently.