Ability to batch apply a tag

I'd like to be able to select all, or some testimonials, and apply a tag to them. USE CASE: I've been collecting testimonials for a single product A, no tags. Now I'm using a separate form to collect testimonials for a different product B. I don't want the B testimonials mixed in with the A ones in my widget, so need to differentiate them via tag. That means retroactively going over all my existing testimonials and giving them the same tag (product A).