What others think you think and what you think they think you think.
别人(猜)想你想什么和你(猜)想他们(猜)想你想什么。
这是两个并列句组成一个长句。
前半句:主语others,谓语think,,宾语think you think(what),该宾语从句省掉引导词that;
后半句:主语you,谓语:think,宾语they think you think(what),这个宾语从句里又包含另一个宾语从句you think----是(they)think的宾语,其中宾语从句前都省掉引导词that.