What does Top 1% mentioned by ATC refer to?
I'm guessing you're referring to a clip such as this one. JFK ground is just being a bit informal and fun (as you can tell from the rest of the clip) with their instructions. Although it isn't mentioned, the controller is probably referring to a business jet flight, such as ExecJet.

The "top 1%" refers to a ranking based on income, specifically those not in the lower 99%. The controller is basically telling them to follow the rich people in their fancy private jet. JustSid found another video where the controller explains it as "someone richer than both you and me."