Canned Comments Plugin?

Been searching everywhere for something that will do this, so any help appreciated.

I have a very busy blog where the comments are basically used as questions and answers. Trouble is I’m answering the same questions over and over in different parts of the site.

What I’d love is a plugin that allows me to create premade/canned answers. I’d then look at the comments box and see a drop-down menu of premade answers I could select and once selected it’d auto-fill the comments text area.

I fear I may have to roll my own!