Usage of ～じゃん　for verbs


> **Possible Duplicate:**  
>  [Usage of ～じゃん
> (～じゃない)](https://japanese.stackexchange.com/questions/1481/usage-of)

usage of ～じゃん for verbs

Sometimes when i talk to a japanese, they use a lot this. I dont know if
there's a rule for it, and when i can or cannot use it.

some examples

> ある **じゃん**
>
> やる **じゃん**
>
> いる **じゃん**
>
> くる **じゃん**
>
> ...

