Oh, BTW, I consider this line to be an absolute classic:
"And if you pull that wand, I'll shove it so far up your ass, your eyes will glow when you say 'Lumos'."
Oh, and the excerpt from Voldie's past, it makes clear that Dumbles -still- hasnt' seen the need to convince his tools to use even a modicum of OPSEC. -shakes head- He's got way too much ego and overconfidence and I reckon he's just over-reached for near the last time. I suspect Harry won't be as quick as Tom wants to be, certainly not when Harry, Hermione, and Daphne work together.
Author's response
I've been amazed at the number of comments that line has gotten...
Sadly, Dumbles, like so many other powerful wizards, might be wise, but isn't very bright.