When a Hebrew word sounds like a naughty word in another language

On holidays and the first day of every ראש חודש new month we say the יַעֲלֶה וְיָבא prayer. There aren't too many English speaking kids who don't eventually notice that the second syllable in the word וּפָקְדֵנוּ (="remember us") like a very raunchy English word. I figured kids of my generation were the first to discover this amusing and childish fact, but my grandfather ע"ה, born nearly a century ago, assured me that even 90 years ago children knew it. In fact, being that last Monday was Rosh Hodesh one presumes that some children noticed it then for the very first time, as must happen every month; some must have muffled their giggle, others couldn't stop.

Of course we are not children and we understand that syllables and even compounds (=words) repeat in different languages. However, the native speaker certainly hears the same sound!

I am told that there is a Teshuvos Rashbatz ¹ which explains an oddity in the pointing of a word in Isaiah 40:5, saying that when we read the verse כִּי פִּי יְהוָה דִּבֵּר "for the mouth of the LORD hath spoken it" in the Haphtarah for Parashat Ve-Va-ethanan, it should be read carefully as written ("ki pi Hashem diber) but should not be modified to read כִּי פִי ("ki fi Hashem diber"), which would seem to be linguistically correct. The reason he gives is that to read it as written out loud sounds blasphemous.

The masoretic Bible commentary Minhat Shai supplies the reason, if it wasn't obvious, commenting on Deut 8:3, כִּי עַל-כָּל-מוֹצָא פִי-יְהוָה יִחְיֶה הָאָדָם "but by every thing that proceedeth out of the mouth of the LORD doth man live":

כל בגד כפת דסמיך ליהוא רפי בר מן המבטלים והרבה מהן שהן דגש להוגן קריה כזה כי לא יתכן לומר פי ברפה קודם לשם כי לשון גנאי הוא בלשון צרפת וחלילה לשם יתברך ע"כ מצאתי: ושמעתי שבלשון צרפת פי ר"ל אין ואפס ובכל הספרים הפ"א רפה כדינה ואין לנו לחוש ללשון צרפת שאין מבטלין דרכי לשון הקדש מפני שאר לשונות ומצאנו עוד במיכה א' כי פי ה' צבאות דבר שהוא רפי

All bgdkpt letters that precede God's name are rafeh [ie, they lack a dagesh and are pronounced softly] except one can't say "fi" before the name, because it is a swear in French, and God forbid one says "Fi" followed by God's name [and therefore this peh should be pointed/ pronounced hard, as "pi"]. That's a view I've seen.

The expression of contempt it is talking about is "Fi." In the codices the peh here is rafeh according to the law and we do not worry about French, since we don't abolish the rules of Hebrew [which require the /p/ to soften to an /f/ before a long vowel] because of other languages.

There you have it. By pronouncing Hebrew correctly, when saying "the mouth of the Lord" it sounds like "Fi, the Lord." Some thought the solution is to say "Pi, the Lord," which is incorrect Hebrew but doesn't sound blasphemous. Minhat Shai asserts that this consideration is invalid.

However, in the case of Isaiah 40:5 a quirk in the pointing allows the reader to avoid saying "Fi, the Lord."

¹ Haven't been able to find it, although I theoretically have access to this.