I know the word 上头 means "go to head" as in 这酒很上头(the alcohol is too strong and people may easily get drunk), but what about 下头 as in the sentence这个渣男真是让人下头？
下头：maybe: be a wet blanket?
The Great God Baidu has this for 下头：
(a) fashionable internet phrase,
has the meanings: dampen one’s spirits
spoil the atmosphere,
be a wet blanket.
The opposite of 上头，
上头 means be absorbed, engrossed in something,
下头 has the meaning: for some reason something or someone makes you lose your enthusiasm or passion,
(something) makes you rapidly lose your feeling of being engrossed or absorbed in something, takes away your enjoyment.
Sometimes we will use 下头 with these emojis 🤢 🤮，which means the behaviors we encounter make us feel disgust or uncomfortable.
下头 is a very latest network phrase, and it often appears in the issues of gender opposition.
For example :
In this sentence, 郭楠 has the similar pronounce with 国男， refering to normal Chinese males who probably do something to annoy girls (However, in some occasions, the boys do nothing wrong, but the girls still think them disgusting...)
Here are some occasions we may think a person is 下头
我和其他模特出去喝酒，有一个哥们不停的在吹嘘多少女人追她，为他是从，我听上去很不是滋味，我们都是190 长相都是属于帅的，谁身边也不缺女孩，而且 女孩喜欢你是认可你，这不代表你可以随便把人家踩在脚下，我们6个人 5个人满脸尴尬 就他越讲越起劲，给我恶心坏了 ---https://www.zhihu.com/question/492860479/answer/2537019213
This above is quted from Zhihu, a Chinese website like Quora.
Even in Zhihu, there is a question talking about : when do you feel 下头 about a person, here is the link https://www.zhihu.com/question/492860479