The inks used in most inkjet printers are water soluble, so you should be able to remove the ink stains from clothing. If you are the victim of a stain at home and can switch into laundry mode quickly, remove the inked garment and deal with it immediately. White fabric can be treated with cold water and bleach before washing, while colored fabrics do better with cold water and sudsy ammonia. You should be able to remove most of the stain using one of these two cleansers and then launder as usual. If, however, it's the office printer that gets you, you'll have to deal with the situation a bit differently.
As soon as the stain occurs, dab at it with a damp paper towel to remove as much ink as you can. Be sure to dab at the ink but don't rub it, as rubbing will only spread it around. When you're finished, allow the stain to air dry.
If you're at home and can change clothes, remove the garment and saturate the stain with hair spray or rubbing alcohol. Once it's wet, press the stain between two paper towels, with one on each side of the garment. Press on the towel that is on the back of the stained garment to force the stain into the towel on the front. Lift as much of the stain as you can in this manner.
Pour some liquid laundry detergent onto the stain and gently scrub the area with an old toothbrush to lift the stain.
Wash the clothing in cold water immediately after pre-treating. After washing, line dry or dry flat to avoid setting any remaining ink stain in the dryer. If you can still see any ink when the garment is dry, pre-treat and wash it again.