In the concerts and theatrical performances in Hungary and certain cities in Romania, unique acceleration phenomenon of hand clapping is often witnessed. This paper reports this accelerating clapping pattern that occurred only in these areas based on the author's investigation. In addition to Western music concerts, this accelerating clapping pattern is likely to occur in highly entertaining stage performance such as theater, musicals and dance, but it is hard to occur in concerts of experimental music, concerts in church, music contests, concerts for each lesson, concerts for children. Loud music with evenly spaced beats also interferes with this acceleration of clapping. This clapping pattern is sometimes created by a large audience, but there are cases where some clapping team guides it. The acceleration in the pattern may be unrelated to the moment of curtain call or bowing on the stage, but usually there is correspondence with such events. It is observed that this accelerating clapping pattern requires the audiences to notice not only their own applause but also the clapping of other audiences with the eyes of a third party rather than enthusiastically applauding.