Aen aen.. shh shh

Yesterday in the kitchen, Shawn insisted my mum to pao pao him near the kitchen window. He said "Aen aen.. shh shh" with his hands doing the shooing action. He repeated it over and over again. My mum told me later at night and both of us were puzzled. On Sunday it was raining cats and dogs and my mum taught him the word rain (Aen). Then I figured he's probably saying this "Rain rain, go away..." He must have learnt the rhyme in school.