v (transitive) To cause a problem with; to introduce an error or mistake in; to make muddled or confused; spoil; ruin.
v (transitive) To cause (another person) to make unwanted mistakes in a given task, usually through distraction or obnoxious behavior.
v (transitive|slang) To discombobulate, utterly confuse, or confound psychologically; to throw into a state of mental disarray.