Okay, so you know how sometimes when you talk your voice sounds a bit different? Well, creaky voice is when your voice sounds really low and rumbly, like a frog or a monster!
When you talk normally, your vocal cords in your throat vibrate really fast to create sound. But when you do creaky voice, your vocal cords are vibrating really slow, which makes a low, creaky sound. It's kind of like when you drag your hand across a rough surface like sandpaper - it makes that rough, scratchy sound.
Some people might use creaky voice to sound cooler or more confident, or you might hear it in songs or on TV. It's pretty neat how we can change the way our voice sounds just by adjusting how fast our vocal cords vibrate!