This app was mentioned in 3 comments, with an average of 1.33 upvotes
Yeah, it's called Gentle Tap. It's not the most neatly designed app, nor most functional, and it hasn't been updated since October, but it does the tap sharing to someone else with the app.
I found one when I first bought my watch but didn't really get a chance to try it.
Might as well give it a go!
https://play.google.com/store/apps/details?id=wearablesoftware.gentletap
Hi. Gentle Tap For Android Wear does exaclty what you want: https://play.google.com/store/apps/details?id=wearablesoftware.gentletap