Someone above mentioned that magnetron bombarded by another magnetron can cause a feedback loop thus causing the explosion. I am not exactly sure if that is scientifically correct but that could be one explanation for the explosion.
But yeah the rest of the story is probably just a meme story.
Nice, It's hard to seperate science from meme these days you know. Back in my day, people wouldn't make such jokes but oh Wait I am still 23. Good times.