I had some first hand experience with a cultural faux pas here in Egypt. I was out with a friend for lunch in a restaurant called Abou Shakra in Garden City. We sat down and ordered some food, only slightly aware of the fact that we were the only foreigners there. I ordered a fresh lemon & mint juice. The juice of the Middle East is spectacularly delicious. I am not exaggerating. It is squeezed fresh, straight from the fruit and without extra sugar. There is always foam on the top too! So here I am drinking my drink and without noticing it, I finished the last of it with one big sip, generating a kind of slurp/gurgle thing. The entire (and I am not exaggerating) restaurant tuned and stared at me as if on cue and began giggling, clearly embarrassed for me. Not knowing how to react, I started laughing too, well aware I just learned an Egyptian faux pas. An Egyptian friend later informed me that it suggests that you are "unclean." I suppose if anything, I would think it would suggest over-indulgence? What do you think?