Harry Potter and the Half Blood Prince2009

[Slughorn is snipping tentacular leaves through a window in the greenhouse. Harry, who is walking by, notices Slughorn and walks up behind him, startling him.]

Horace Slughorn:
[Gasps in surprise] Merlin's beard, Harry!

Harry Potter:
Oh, sorry, sir, I should've announced myself. Cleared my throat. Coughed. You probably feared I was Professor Sprout!

Horace Slughorn:
Yes, I did actually! ...What made you think that?

Harry Potter:
Oh, well, just the general behavior, sir - the sneaking around, jumping when you saw me... Are those tentacular leaves, sir? They're very valuable, aren't they?

Horace Slughorn:
Ten Galleons a leaf to the right buyer! ...Not that I'm familiar with any such back alley transactions, but one does hear rumors. My own interests are purely academic, of course.

Harry Potter:
Personally, these plants always kind of freak me out.