You can mine his yard.
What you do is:
Take a plastic bottle, this can be any Coke bottle. Now take a drill(a knife works fine also), and drill two holes on the same side of the of the bottle, but at opposite ends. Try to put each hole about two inches from the middle. Now put some strong tape over the holes, and fill the bottle up with water(the tape is for keeping the water from flowing out).
Go over to your brothers house, and place the bottle on the ground with the holes facing up. Be sure to put the bottle(or bottles) in a place where your brother is likely to step, like a path he takes to get to his car.
Take the tape off the holes, and cover the bottle with grass, leaves, and dirt(but make sure not to get any dirt in the water), in order to camoflauge the bottle.
When your brother steps on the bottle the water will shoot up out of the two holes, soaking your brother. These work much better than just putting water ballons on the ground. Last summer I tested one of these water-mines on myself, and the water squirted up to my nose!
Also, the water can be contaminated with something foul-smelling, or something that may sting the skin or make him all sticky, such as lime-juice. It can be especially bad in cold-weather.
But, obviously, you don't want anyone to see you setting these up around your targets home, so it may take some stealth and the cover of darkness for it to work!
