He replied "No! We don't have glass "off" water here"
I looked at him, and saw his silly face. I knew that he was teasing me, so I didn't say anything just looked at him like asking 'common, are you kidding me?'. While laughing, he said: "I can give you a glass of water".
The problem here is that I pronounced of with the letter f at the end. However, the letter f in this word is pronounced like v. If you pronounce the letter f you are saying 'off' that is the opposite of 'on'.I have seen many foreigners mispronouncing this word like me. Even that people know what we are saying by context, it would be better if we say it correctly.
This video is really useful to understand and practice how to pronounce of in an American English pronunciation.