It makes sense when you say it aloud. :) "Naah! go do somem wif em!" ="No, go (and) do something with them!" Someone's slurring their words.

Whoever is speaking is telling you to go do something with them.

hey ...Lina are u remember me ? why dont u contact me ?

Nah, go do something with him. It seems like ebonics (poor English used by somr American blacks)

I bleive we had a convo bout dis already... Okay that was a very bad attempt at trying to be like your friend.