Question

ʃ English shoe, fish. Spanish does not typically have this sound, but in the River Plate region of Argentina-Uruguay, some people pronounce the y and the ll this way: yo, pollo. Some dialects in parts of Spain and Mexico pronounce the ch this way: chico, muchacho.

Accepted Answer

Voiceless Palato Alveolar Sibilant http://en.wikipedia.org/wiki/Voiceless_palato-alveolar_sibilant

Symbol	ʃ
Name	Voiceless Palato Alveolar Sibilant
Notes	English shoe, fish. Spanish does not typically have this sound, but in the River Plate region of Argentina-Uruguay, some people pronounce the y and the ll this way: yo, pollo. Some dialects in parts of Spain and Mexico pronounce the ch this way: chico, muchacho.
Ref	http://en.wikipedia.org/wiki/Voiceless_palato-alveolar_sibilant

Ch O Sibilant Sh Pronounce Y Ll ʃ