"Bug ba-design, zayin ba-debug" (Hebrew: באג בדיזיין, זין בדיבאג)
I feel sorry for the majority here - non-Israelis who can't get this joke - because it's truly one of the funniest things I've heard in a while. It is a clever play on words, even though it mixes English and Hebrew and isn't all that grammatically correct (it's not even a complete sentence). Remarkably, it is a fact of life as well.
The word zayin (slang for "dick" in Hebrew, pronounced similarly to "sign" in "design") has some of the connotations the word shit has in English. The phrase, therefore, can be translated as "A bug in the design (is) shit in the debugging" or "A bug in the design (is) shit to debug". Another way to interpret this usage of "zayin" is as a shorthand for "lekabel zayin" (lit. "to get dick" - to get screwed; carries very rude connotations), and then a loose translation could be "If there's a bug in the design, you get screwed when you debug".
The original writeup above (which is no longer with us) said this was a common mantra among Israeli programmers. Well, not common enough for me to have heard it before, I guess, but its appeal is understandable.
If there are any programmers reading this - Try making bug ba-design, zayin ba-debug your mantra. Say it aloud three times at the beginning of every coding session, and feel the ancient magic of Hebrew wash over your code in blissful obscenity. You can also remind yourself of it whenever you get screwed (proverbially) debugging improperly designed code.