YOU SAID:

Seth likes when he gets sand in his swim shorts at the beach. He fills his pants with water and swishes it around.

INTO JAPANESE

セスが好ききたらビーチで彼の水泳パンツで砂。彼は彼のズボンを水でいっぱいし、周りを swishes します。

BACK INTO ENGLISH

Seth is like if you come on the beach in his swimming trunks sand at. He is in his pants and filled with water, the swishes around.

INTO JAPANESE

セスは彼の水泳パンツ砂のビーチで来ればわかるようです。彼は彼のズボンは、あふれた水に周り swishes。