说你胖 你还喘上了 来劲儿了 how does this translate in english in this context? I'm trying to figure out what the sentence in the title means in this context: 

A gang of punks has just beaten a retarded guy and another guy, who saw what was going on, tries to stop them but he gets beaten too. The latter is part of another gang and few time after they decide to punish them attacking one of the members, so a guy of the second gang uses a brick to crack the head of one of the "bullies". Then the guys who took part to this expedition talk together about what just happened and here's what they say:


A: when'd you get to be such a thug? ( 你丫的手怎么这么黑呀 )
B: What do you mean? ( 怎么了 )
A: What you did with that brick... even I was was spooked. ( 那板砖拍得 连我都怕 )
B: It was dark. I couldn't see, otherwise I'd have really wasted him. ( 天太黑 看不清楚 要不然非废了丫子的 )
A: 说你胖 你还喘上了 来劲儿了 (?)


I think it's some sarcastic answer to make him notice how he's full of himself, but I can't really understand, I'd like to be able to translate it but I can't.
I think it's some sarcastic answer to make him notice how he's full of himself


Yes, that's basically what it means. 

“说你胖 你还喘上了” literally means, "you start (pretending) to breathe heavily soon as you're said to be fat", it is an expression/slang used metaphorically to say someone's pretending to be (more of) something he/she is said to be (usually out of courtesy).

I personally found it as hilarious and offensive at the same time. An example,
A: "You know what, a friend of mine just said you look cute."
B: "Yeah, I actually hear that a lot."
A: "说你胖 你就喘"

Someone "来劲儿了" means someone is pumped. In the given context, I understand it as that B took A's words as an acknowledgement and got pumped.