hi thanks everyone!  i think i've got the point!

but what if i graduated from the ESL school later and then he asked?  is it appropriate to have a drink with him because i just wanted to make friends, 

Hi I am an ESL student and currently travel to USA to learn some English and the culture.   I know sometimes there are hidden meanings in the everyday slangs and recently a male teacher asked me to "have a drink some time with him."  I don't know if it's really have a drink or there's more, you know, romantic hints or something.  And forgive me that I don't quite understand the western culture here.

Anybody could help me out to decode this please?  Thanks.