I've never heard that and I'm stealing it.

Come on, don't downvote someone for learning something (you think is) well known for the first time. Especially when their response is "that's great and I'm going to use it". https://xkcd.com/1053/

The comment is noise - no different from "+1" or "me too". If you found a comment helpful and want to thank someone for it, the way to do that is an upvote.

It's a bit different, I added that I had never heard of the phrase and that I would be using it.