Hello,
So, the context is pretty easy to explain this time. A girl suddenly kisses the boy, and the boy, surprised, pushes her away. She asks him why and he responds with あーゆーことされたら、普通理由とか聞いてくるところだろ!!
Firstly, who is the subject of the second sentence? I'm assuming it's people in general, so I would translate this as "When they are being done something like that (I know, it doesn't sound natural), normally, that's the part when one would ask for a reason."
The problem is, I don't understand why てくる is necessary. Is it "they would go and ask for a reason", just like when you command someone to go do something (e.g 果物を買ってくる)?
If the subject would be "you", "the girl", "the one who kissed him", then I would understand...she should come to him to ask for a reason, except this doesn't seem right, according to the context.
Second thing, the usage of ところ. I'm assuming it's not this: (after present form of a verb) about to; on the verge of. ところ is used here to basically say "a point in time" or "the part when" (as I translated it), right? I made this assumption about ところ long ago, but since I didn't ask anyone, I still have a very slight doubt that I'm understanding this right.