When you're distracted, everything you do is a fluke. You're not focusing, so it all comes down to chance.
Note that this word is mostly written in kana only!
Since this word consists of a kanji with hiragana attached, you can bet that it will use the kun'yomi reading. This uses a different reading than the one you've already learned, so here's a mnemonic to help you:
Somebody was trying to mug (まぐ) you, but you managed to escape by pure chance! Your escape might have just been a fluke, but at least you didn't get mugged!
It was just a fluke that I was able to answer the questions on the quiz.