"Soon by you" is one of those odd little phrases. The vast majority of the time, it's meant as a blessing from a kind and loving place. But it gets very old very, very quickly, being heard as, "So, when are you getting married/having a baby already???"
A few weeks ago, however, I heard the perfect application for this phrase. At my office, we eat lunch in shifts. A later eater stopped by the kitchen to get coffee, and wished the assembled early eaters, "B'teavon!" ("Bon appetit!") As you may have guessed by now, one of the early eaters thanked them and said, "Soon by you!"
Speaking of which, I'm trying to get back in the habit of wishing any eating Israeli "B'teavon". This little phrase is really not part of the American culture, but it seems that here, not telling an eating person "B'teavon" is equivalent to not telling a sneezing person, "Bless you." Not the worst faux pas, but it really is rude.
