In the Tale of the Pinyin Pirate 拼音海盗人, the 2CC teach you how to pronounce the retroflex sounds 卷舌音 in Mandarin Chinese, represented in the Pinyin Romanization system as: zh- (zhi), ch- (chi), sh- (shi), r- (ri) & -r (er).
The Two Chinese Characters (2CC) are John B. Weinstein & Carsey Yee. Video produced by Jamie Ciocco.