What does "thanking the bus driver" do?

I was gone on vacation, when I came back , and checked fortnite, in a battle, there were so many

Player X has thanked the bus driver

at the start of a game.

Does this do anything if I thank the bus driver(Pushing the EMOTE key)? Or is this a funny useless thing added thing by epic?

It does not provide any gameplay advantage to thank the bus driver. It is just a little fun thing, probably based on the "thanking the bus driver makes you a better/more successful person" meme.

Source: https://www.gamerevolution.com/guides/421551-fortnite-bus-driver-how-to-thank-the-bus-driver-in-fortnite

Thanking the bus driver does nothing, as @Crovaxon said, but it is used for some challenges (typically non-weekly/daily challenges).