Sometimes it would cause others to experience terrible things, while things go great for the character with the power.
Despite being called Probability Manipulation, in most cases the power was uncontrollable by most people.
For example, Hula-Hula usually only experienced bad luck, causing him and others around him to experience unlikely freakish events, like stepping on a rake and having it slam them in the face for example...almost like something you'd see in a Looney Tunes animated short.
Sometimes though, things would go well. For example, Hula-Hula always seemed to run into someone he knew no matter where the National Bureau of Investigation's assignments would take him, Plastic Man and Penny. This often proved helpful to the trio, because they'd often get the help they need at the right time they needed it.