What does 「なにしてたん？」mean?


I've been talking with a Japanese exchange student at my college. For 4 years
I've been studying Japanese and we get along just fine most of the time but
sometimes even I get a bit lost.

He's from Kobe so perhaps it's a part of his dialect.

My question is, what does「なにしてたん？」mean? The main thing that confuses me is たん.




> **何をしていたのですか？** : Root
>
> **何をしていたの？** : Drop formal ending.
>
> **何していたの？** : Colloquial drop of particle.
>
> **何してたの？** : Colloquial drop of syllable.
>
> **何してたん？** : Lazy end turns の into ん.

