形狀上真的有圈
這一組就是核心畫面本身，沒有比喻：東西真的繞成一圈一圈。
adjective · B2
Full of loops: made of lines that curl round and round instead of running straight. Used about tracks, roads, handwriting and anything else shaped in curves and circles.
有圈圈的、繞來繞去的
核心畫面
You can think of loopy as a line that will not go straight. Instead of running from one point to the next, it curls back on itself again and again: rollercoaster track turning a full circle, handwriting full of round curls, a mountain road folding back six times. Hold that curling line, then put it inside someone's head, and most of the other uses of the word open up.
loopy 的核心畫面可以想成一條不肯走直線的線。它不是從 A 直接到 B，而是一路捲、一路繞，甚至繞回自己身上。雲…更多收起
loopy 的核心畫面可以想成一條不肯走直線的線。它不是從 A 直接到 B，而是一路捲、一路繞，甚至繞回自己身上。雲霄飛車的軌道翻整整一圈、字跡圓圓捲捲、山路一彎再彎，都是這條線。把這條繞圈的線放進腦袋裡，這個字的其他用法差不多就通了：想法接不上直線，就是怪怪的、暈暈的、快撐不住了。From the word’s history
Wiktionary gives loopy as loop + -y. The literal shape sense sits right on that build, and the head senses read as the same picture moved inside a person.
Wiktionary 記載 loopy 來自 loop（圈圈）加上 -y（有…的樣子）。形狀上的意思最貼近這個字面組合；講人、講腦袋的用法，讀起來像是同一條繞圈的線被搬到人的裡面。
Wiktionary entry for loopy (packet etymology_text): From loop + -y.
Three branches
腦袋沒走直線
把那條繞圈的線放進腦袋：想法接不上直線，於是聽起來怪、反應也慢。這一組都是口語。
adjective · B2
Strange or silly in a way that does not seem sensible. Used in casual talk about a person, an idea or a plan, usually lightly and with a smile rather than as a serious complaint.
瘋瘋的、怪怪的
固定說法 go loopy
這兩個意思屬於 go loopy 整組字，不是 loopy 自己帶的。動詞 go 帶出「突然變成那樣」，所以畫面從「一條繞圈的線」變成「本來直的線突然捲起來」。
adjective · C1
If someone goes loopy, they suddenly become very angry and show it, usually loudly and in front of other people.
抓狂、大發脾氣