Hey! Where are you going? -- I'm going shopping.

[MyEfforts]

Hi,

I'm going to write down what happened ? when I was going shopping. Please check the grammar and also suggest me when you find any sentence which Native speakers speak in a different manner:-

I was walking down the street and one of my friend comes across me and said:-

My Friend:- Hey ! Where are you going?
I:- I'm going shopping.

My Friend:- O' that's great, but for what ?
I:- For jeans , yesterday I went shopping for pullovers, it was a good day and I want to make today good as well

My Friend:- Can I accompany you ?
I:- Sure....sure! why not.

[Morteza]

Hi,
While I was .................... , one of my friends(NOT friend) ... came ..... .
... great.But for what?
To buy a pair of jeans.Yesterday .............. ;(NOT ,) ................... .
..........!Why not?
Regards,
Morteza

[MyEfforts]

Thanks Morteza, as per your suggestion, I tried my best to understand what pointed me and I rectified my mistakes. Please have a look:-

[Kate_Zam]

While I was walking down the street, one of my friend came across me and said:-

My Friend:- Hey ! Where are you going?
I:- I'm going shopping.

My Friend:- Great, But what for ?
I:- To buy a pair of jeans. Yesterday I went shopping for pullovers; it was a good day and I want to make today good as well

My Friend:- Can I accompany you ?
I:- Sure....sure! Why not ?

[MyEfforts]

Kate, I'm afraid but I reckon both ways are right:-

[Morteza]

Hi,
You can say,"while walking down the street, I came across one of my friends."
Because when the subjects of the sentences are the same, we can use reduced adverb clauses.
"Semicolon" is used for connecting 2 sentences without any connectors:
Turn down the TV;(=because) I am studying.
Regards,
Morteza

[MyEfforts]

Morteza thanks for answering. I got it.

I'm afraid the example you gave me it should have been