This is the 682nd most frequent Chinese word.
雷
"雷" means "thunder."
In this sentence, '雷' refers to lightning and thunder typically seen in thunderstorms.
今天的天空很阴暗，好像要下雷雨了。
Today's sky is very dark, it seems like there will be a thunderstorm.
Here, '雷' is used colloquially to describe something shocking or surprising in a humorous or sarcastic sense.
他的笑话太老了，简直让人觉得很雷。
His joke is so outdated, it really feels shocking.
In this example, '雷' refers to something unexpected or remarkably attention-grabbing, often with a surprising or unconventional aspect.