Berakhot 62A

תניא, אמר רבי עקיבא: פעם אחת נכנסתי אחר רבי יהושע לבית הכסא, ולמדתי ממנו שלשה דברים: למדתי שאין נפנין מזרח ומערב אלא צפון ודרום, ולמדתי שאין נפרעין מעומד אלא מיושב, ולמדתי שאין מקנחין בימין אלא בשמאל. אמר לו בן עזאי: עד כאן העזת פניך ברבך?! אמר לו תורה היא, וללמוד אני צריך.

It was taught in a baraita in tractate Derekh Eretz that R' Akiva said: I once entered the latrine after my teacher R' Yehoshua, and I learned 3 things from observing his behavior: I learned that one should not defecate while facing east and west, but rather while facing north and south; I learned that one should not uncover himself while standing, but while sitting, in the interest of modesty; and I learned that one should not wipe with his right hand, but with his left. Ben Azzai, a student of R' Akiva, said to him: You were impertinent to your teacher to that extent that you observed that much? He replied: It is Torah, and I must learn.

תניא, בן עזאי אומר: פעם אחת נכנסתי אחר רבי עקיבא לבית הכסא, ולמדתי ממנו שלשה דברים: למדתי שאין נפנין מזרח ומערב אלא צפון ודרום, ולמדתי שאין נפרעין מעומד אלא מיושב, ולמדתי שאין מקנחין בימין אלא בשמאל. אמר לו רבי יהודה: עד כאן העזת פניך ברבך?! אמר לו: תורה היא, וללמוד אני צריך.

Similarly, we learned in a baraita: Ben Azzai said: I once entered a latrine after R' Akiva, and I learned 3 things from observing his behavior: I learned that one should not defecate while facing east and west, but rather while facing north and south; I learned that one should not uncover himself while standing, but while sitting; and I learned that one should not wipe with his right hand, but with his left. R' Yehuda said to him: You were impertinent to your teacher to that extent? He replied: It is Torah, and I must learn.

רב כהנא על, גנא תותיה פורייה דרב. שמעיה דשח ושחק ועשה צרכיו. אמר ליה: דמי פומיה דאבא כדלא שריף תבשילא. אמר ליה: כהנא, הכא את? פוק, דלאו ארח ארעא. אמר ליה: תורה היא, וללמוד אני צריך.

On a similar note, the Talmud relates that Rav Kahana entered and lay beneath Rav’s bed. He heard Rav chatting and laughing with his wife, and seeing to his needs, i.e., having sex with her. Rav Kahana said to Rav: The mouth of Abba, Rav, is like one whom has never eaten a cooked dish, i.e., his behavior was lustful. Rav said to him: Kahana, you are here? Leave, as this is an undesirable mode of behavior. Rav Kahana said to him: It is Torah, and I must learn.