But in case my predictions are right, maybe you should buy a new pair of shorts?

predictions 是名词 prediction 的复数形式。prediction 由前缀 pre-（表示"在...之前"）和词根 dict（表示"说"）以及名词后缀 -ion 组成，字面意思是"提前说出的话"，即"预测、预言"。