The Importance of Mass in Quantum Physics

As you approach the speed of light, I thought Einstein's equations told us that you would gain mess but to an outside observer I don't think you would actually look bigger. Maybe space gets contracted so kind of brainstorming here. If we consider energy as being mass you know the way it works relativistically you can concentrate energy as well as matter and that is all mass energy then as you add velocity you're adding energy and you become more massive. Do you think you should stay in your couch if you don't want to gain any mess? Here's what people had to say.