chicken out的含义不是指“小鸡在外面”，其正确的含义是：（因害怕而）退缩，放弃。

【例句】
I was going to go bungee jumping, but I chickened out.
我原打算去玩蹦极跳的，可是因为害怕放弃了。

I had never ridden on a motorcycle before. But it was too late to chicken out.
那以前我从没骑过摩托车。不过，想退缩已经来不及了。