Beatboxing

Beatboxing is a vocal imitation of any types of percussion, turntables, or other instruments. It could also involve some singing. Modern beatboxing style has its origins in the early styles of hip-hop, but the art of vocally imitating instruments existed long before that. Although vocal percussion has probably existed just as long as man, such an imitation of instruments first existed in the U.S. in the form of "scat." Scat was an improv style used by jazz singers in order to imitate instruments such as saxophones and trumpets. Today, beatboxing is quite popular and can be a very competitive style of music. It is similar to freestyle rap in that respect.

History of beatboxing: http://www.humanbeatbox.com/history/p2_articleid/27
Scat's enclyclopedia article: http://www.britannica.com/blackhistory/article-9066055