Floating see through thumbs up - what does it signify

I am regularly seeing a ghost looking thumbs up spinning over someones head for a few seconds.  What is it?

It’s a “Ride On” given to the rider by another rider as a means of support. Like a “Thumb’s Up” on Facebook. It’s just a way to tell a rider than you appreciate their effort or whatever.

Would be nice to see the name of the person who gave you one, on Strava, Facebook etc, you can see who gives you a like or kudos.  

Seems a bit weird to get a random thumbs up from people without knowing who or why, also makes it hard to respond in kind.

@Matt: if you look on your Zwift Dashboard on the web it will show you what rides you collected “Ride Ons.” It shows up in a little blue box with the thumb and a number to the left of the ride in your list. If you click on the box it will open a pop-up that will show you a list of all the people that gave you Ride Ons for that ride.

I think it tells you who gave you a ride on up the top of the screen if you look at the right place at the right time.