The term 'Sousaphone Cousin' is a reference to the TUBA, which is a four-letter word. The TUBA is a large brass instrument that is part of the brass family of instruments. It is usually played with a mouthpiece and has a conical bore. It is most commonly used in orchestras, marching bands, and jazz ensembles. The sousaphone is a type of TUBA that was designed by John Philip Sousa and is often used in marching bands. It is characterized by its large bell and curved shape, which makes it easier to carry while marching. The sousaphone cousin is a variation of the sousaphone that is slightly smaller and more compact than the traditional sousaphone. It is still used in marching bands, but is also popular in jazz and other genres of music.