Is this grammatically correct?

My friend was trying to show me and other friend something on the internet and he said "this will blow you away". After watching the video for 5 seconds I said sarcastically "wow, I am blown away". Then everybody started laughing and repeating what I just said. At first, I thought they were laughing with me but they kept bringing it up to my other friends, I didn't think it was that funny. So I thought maybe I made a grammatical error, since they like to make a fool of me everytime i make a small mistake because english isn't my first language. So, was it grammatically incorrect what I said?