Oh Sarcasm, How I Have Missed You!

The following conversation took place last night has I was studying.  I was listening to music trying to study. When my flatmate came in ( Note: He is a really nice, sweet guy he just happened to have caught me a particular smart-assy moment) and heard the German song that I was listening to (http://www.youtube.com/watch?v=11LzBOPtJVs) . Linguistic hilarity ensues.

Carston: Hello!
Me:  Hey, whats up? (Goes back to lip-syncing the song)
Carston: ( listen to the song and gets a puzzled look) What are you listening to?
Me: Arschgesicht  by the Bangbros ( Ass-Face in english, the whole song is strange, but its got a good beat)
Carston: Do you know what they are singing about?
Me: (Looking at him with a smile on my face) Nope I don't have a clue what they are saying even though I am a German major.
Carston: Okay well the chorus is about someone having a pretty ass-face and.....
Me: No....No Carston, I was being sarcastic.
Carston: I dont know this word in english.
Me: (I dont know Sarcastic in german) Well its when you say something but you mean the opposite.
Carston: (Puzzled look returns to face) So you were trying to tell me you do understand and your not a german major?
Me: No...no!!! Your right about the first part, the second part was to try to make my sarcasm more obvious!
Carston: Oh lol. I think I get it now....thanks
Me: (Get ready Big Bang Theory fans) Geez I think I need to hold up sarcasm sign every time I am joking.
Carston : (Laughs nervously) You dont need to do that. I know it now.
Me: (Slumps over the table in laughter) I was kidding!
Carston: Oh lol. I guess you got me.
Silence for about 5min.
Carston: (Looks at me and smiles) Thanks for the lesson in sarcasm, your going to be a great English teacher!
Me: Oh, thanks.
(Carston laughs and walks away)
Me: Wait............Was he being sarcastic????!??!?!