Meaning of 変なテンション


What does `変なテンション` describe?

To my limited understanding, the expression is used by a person who observes a
`テンション高い` person but fails to understand why that person is `テンション高い`.

Am I mistaken? Or is there more to it?  
Are there requirements that the observer or observed have to fit in for the
expression to be used?  
In any case, 変なテンション has nuances that are not conveyed by just the sum of 変な
and テンション (in its Japanese meaning of course).

No dictionary in sight in the first few Google pages.

Usage examples:

  * `変なテンションになっちゃう` has [30.000 Google results](https://www.google.com/search?q=%22%E5%A4%89%E3%81%AA%E3%83%86%E3%83%B3%E3%82%B7%E3%83%A7%E3%83%B3%E3%81%AB%E3%81%AA%E3%81%A3%E3%81%A1%E3%82%83%E3%81%86%22)
  * 昨日の夜ゆきちゃんと変なテンションで 撮った動画です(￣▽￣) 笑
  * 石を落とさないようにしているのか、カワウソが変なテンションで遊びに夢中になっている姿がかわいらしいです。
  * 焼肉でありえない変なテンションになっちゃう
  * 守衛さんの「ふーん大丈夫かこいつらー」が他人事っぽくてよいです。でも確かに残業してるとこんな変なテンションになっちゃうことありますよね。
  * しかし、この日は何故か大野が変なテンション。“興奮してるでしょ？”“俺と付き合うか？”など、爆弾発言を連発させる!?
  * xxxくんは変なテンションで車を紹介しながらむき出しになった後輪のタイヤに乗って「タイヤに乗れるんだよ」と無邪気にはしゃいでいたのが可愛い(・∀・)




First, a brief explanation of the word 「テンション」 for those who are not familiar
with it. It does **_not_** mean "tension" or "tense". Rather, it refers to
**_"(a level of) excitement or hyperness seen in a person"_**.

「テンション」 is such a frequently-used word that I had to define it first. I know
from my personal experience that quite a few J-learners would think that it
meant what the word "tension" meant in English.

The phrase 「[変]{へん}なテンション」 can be used to refer to many different kinds of
excitement, hyperness, etc. because the word 「変な」 itself is a very broad word.

It would generally refer to a weird, unusual, unexplainable or unexpected kind
of excitement observed in a person. The phrase is highly inclusive and it can
be used in many situations.

Finally, I think your observation is valid in that the phrase 「変なテンション」 is
used much more often when one's テンション is rather high than when it is low.

