lol, actually it is a Cantonese dialect, well it is not a good expression, and it is usually used to express that you hate someone awfully then you can say to him that 你去扑街了！which means that go to the hell, go to die, shit~~~~~~~~ And this express ususally be pronounced as "poor guy" in Cantonese dialect.

應作 仆街 http://zh.wikipedia.org/zh-tw/%E4%BB%86%E8%A1%97

The original mean of 扑街 is failing down on street. Now it's meaning is that to go to die, to fail down and die on the street, get way.It's a sentence to show the speaker's hate to a person and want this listener vanish away.

Fell down in the street. "Bastard" in Cantonese, swear words to curse or, generally has the following meanings: 1, walking dead. The equivalent of "die" or "roll". For example, you bastard. "!" 2, bastard. For example, "you bastard!" "you are a bastard!" 3, the interjection, meaning "bad".

扑街In the Hong Kong,it is a common saying in the Hong kong,If you make something trouble,you can say it.In this situation,it means very awful.Sometimes if you want to call names,you can use it.In this situation,it means shit.Absotely,sometimes if you say it,but it does not mean shit.For example,仆街仔呀，这样你都想的出来.So,in this situation,it means little kid,you are smart to come up with a good idea.