It's very easy to double-tap on the screen, then hit “Select All”… and it's even easier to accidentally hit the backspace key on your Bluetooth keyboard, causing the writing you were working on to go poof.
What's even funnier is when you're at the local coffee house doing this, and you realize you did it. Frantically leaping to your feet, muttering “awwwww shiiiiittttttt”, and then shaking your iPad like a four year old with an Etch-A-Sketch will cause the rest of the folks in the coffee house to laugh at you.
However, this WILL ensure you get your writing back.