The most effective way to prank your friends is to be prepared.
Invest in an arsenal of whoopee cushions, rubber chickens, and a good supply of silly string.
Study your mark's behavior patterns, anticipate their weaknesses, and strike when they are most... distracted.
Be prepared to improvise, think on your feet, and adapt to any situation.
Remember, a good prank is all about the art of misdirection and miscommunication.
But most importantly, always have a fire exit plan. You never know when things might get out of hand... or when your mark might just get you back.