The word "JEAH!!!" is an interjection that can often be used in the place of "Yes" by individuals who prefer to answer simple questions with extremely loud and inappropriate responses.
"JEAH!!!" can also be used in agreement of something that is not a "yes or no" question, similar to saying "that's awesome." Often this interjection can be used at random intervals when no questions are even asked or in the middle of an awkward silence.