I do not think that my teacher meant this remark to be funny, but I think he was saying a lot with his remark. I am reminded of it often when I see people who do not study the Torah and know little about it, kiss the Torah when it is brought from the ark to the podium to be read on Shabbat.
When I finished high school at Talmudical Academy in Baltimore, Maryland, I attended Yeshiva University for a year and a half and then returned to Baltimore where I went to Ner Israel Rabbinical College during the day and Johns Hopkins University at night.
While I was sitting in a class studying Talmud at Yeshiva University, a student opened the door and arrived late. He reached up his right hand, touched the mezuzah, and then kissed his fingers that touched the mezuzah.
The rebbe turned to him and asked, “Why did you kiss the mezuzah?”
The student replied, “Because it is a mitzvah.”
The rebbe said, “Circumcision is also a mitzvah.”