Short for "Are you lagging too?"
A phrase a person will say in online games if they experience connection problems. After this being asked, the other players will reply "yes" or "no" depending on if they lag too. The point of this is to know if the server they're playing on is having issues or it's the individual
player's
internet.
If everyone replies"no", you can be sure that your own
internet is the problem, however if they reply "yes", it's most likely the server.