I'll tell you what happened to him. A certain someone had a senior moment.

我来告诉你是怎么回事吧。某人得了老年失忆症。

I thought, maybe he was having a senior moment.

我想，也许他是老糊涂了。

Yann says that having a senior moment or losing your train of thought is " what happens when you are over the hill" (hill).

Yann 说，拥有高级时刻或失去思路是“当你翻过山峰时会发生什么”（hill）。