The human beatbox is the art of reproducing all types of sounds with the mouth while 'adapting' them for better control. To understand how these 'voice virtuosos' juggle with so many different sounds--instrumental, rhythmic, and vocal--at the same time, we have performed a descriptive analysis of three beatboxers by observing their vocal tract behaviour by fiberscopic imaging using an OCM visual scale. From an anatomical-dynamic point of view, beatboxers mobilize all the structures of their laryngopharynx separately. With this first physiological study of the human beatbox, we could observe a well-developed laryngopharyngeal system with extreme articulatory configurations to perform their art.