Quantum fluctuations are like the in-laws of the quantum world: they're always dropping by unannounced and messing with your head.
Imagine the universe is like a big, messy kitchen. You're trying to cook up some nice, neat particles, but they're constantly wobbling and wiggling about like a toddler on a pogo stick.
And then there's the infamous "Schrödinger's cat"... just chill, kitty. You're not really dead or alive. You're just stuck in an endless loop of "maybe" and "probably" and "definitely not".