I learned the meaning of 大気 and always forgot if it’s tai or dai.
Then I realized that this word reminds me of something - if you ever watched gaki no tsukai you might understand. 
Now I always think about Tanaka getting a Thai Kick and this is how I remember that it’s written taiki.
For everyone who doesn’t know what the hell I’m talking about, enjoy:
lmao that’s literally what i used to remember 大気. i’m glad i’m not the only one!
Omggggg that’s amazing 
大 is one of the kanji I’ve come to dread seeing in vocab since it has two readings that are almost identical; I get the だい and たい readings mixed up all the time. I should probably get in the habit of coming up with wacky mnemonics of my own for cases like these.