It is a nonsense phrase. It breaks Japanese grammar rules. It misuses English. And that is exactly why it is perfect.
Frequently Asked Questions (FAQ) Q: Can I use this for my girlfriend? A: No. The "otouto" (younger brother) specificity is crucial. Using it for a girlfriend changes the subtext weirdly. Use "Uchi no kanojo" at your own risk. uchi no otouto maji de dekain verified
You open your fridge and find a watermelon that has grown to the size of a yoga ball. You take a photo. You caption it: "Uchi no suika maji de dekain verified." It is a nonsense phrase