It’s easy to lose focus during language classes, especially once you’ve reached that level where the class is conducted exclusively in the target language. If you don’t maintain your concentration consistently, you’ll start to miss words here and there, the meaning of what the teacher is saying will start to fray, and eventually you’ll find yourself gazing out the window, wondering exactly why it is that airplanes don’t sink like stones.
My senior year Japanese professor was great at keeping everyone’s attention. She rotated between a variety of topics, even literature, and knew that to keep everyone’s attention it helps to be silly. I’ll never forget the way she played up her love for Yon-sama or the way she used to laugh whenever we said something silly. (On a quick, somewhat-related side note, nothing more effectively disarms and simultaneously entrances Japanese elementary school students than an English teacher who doesn’t care about looking or sounding like an idiot.)
One of the topics that she taught was “Airbag Expressions” (エアバッグ表現). This may be the single most useful thing I ever learned in a Japanese class.
Let me let that sink in…
THE SINGLE MOST USEFUL THING I EVER LEARNED IN CLASS!
She had a theory that requesting something of a Japanese person was the equivalent of a head-on collision; without deploying a proper linguistic buffer – the airbag – the Japanese person may be shocked beyond recovery, and it is unlikely you will ever get what you want.
She taught us a number of incredibly useful phrases that help warn Japanese people that you are about to ask for something and other ways to lighten the actual request itself. The two that I use most frequently are: 恐縮（きょうしゅく）ですが and （もし）ご迷惑（めいわく）でなければ、
恐縮 is a difficult word to translate into one word in English, so let’s look at the kanji themselves. 恐 means fear or awe, and 縮 means shrink, so when the speaker uses it, imagine him literally afraid of what he is going to ask for, shrinking away from the requestee. One of the nicest translation in English is “It’s terrible of me, but…” or “It’s terribly selfish of me, but…”
(There’s definitely an element of brushing away selfishness with the term; it’s often used as a response to heaps of praise: 「おめでとう！大変上手にできました」“Congratulations! You did a fantastic job” 「恐縮です」 “It was nothing.”)
So you could use it like so:
「恐縮ですが、来週の火曜日休ませていただいてよろしいですか。」
or
「恐縮ですが、ホチキスを貸してくださいませんか。」
(Although, maybe borrowing a stapler is not exactly weighty enough to call for a 恐縮.)
（もし）ご迷惑でなければ is a conditional clause. もし is not necessary, but it does help emphasize the fact that what you are about to say is conditional, and it reinforces the –ば. なければ seems confusing at first, but it’s just like あれば, really.
あれば = if something is/does X
なければ = if something is not/does not X
So, ご迷惑でなければ means, “If it isn’t a bother/trouble/problem…”
You can use this in almost identical situations as 恐縮, and you can even use them alongside each other:
「大変恐縮ですが、ご迷惑でなければ、推薦状を書いていただけませんでしょうか。」
“It’s terribly selfish of me to ask, but if it isn’t too much trouble, do you think you could write a recommendation for me?”
These are powerful expressions and should only be used for the most noble of purposes. Save them for a time when you need to make an extremely difficult request, one that might otherwise be denied. I am guilty of throwing these around too freely and have been trying to expand my set of エアバッグ表現 so that I have a larger selection to choose from. (「悪いですが、」, I choose you!)