This is language that people use on the internet. a troll is someone who makes jokes/someone who is lying/someone who is not serious. "obvious troll is obvious" is a strange way to say "you are an obvious troll". this means, the person who said this to you thinks that you are making a joke/not telling the truth about something. big boy is also a way to say "guy, dude, bro" bro is short for brother, and this is what males often call each other on the internet. It seems like you said something that this person didn't take seriously. This person thinks you made a joke, and they do not believe you. Don't worry about this.