Eiruvin 44b: One may form a wall out of people to permit carrying on Shabbos, but only if the people don’t realize they are being used as a wall. Once, Rava had some bottles that were lying in the street of Mechuza. As Rava walked home from his shiur, surrounded by talmidim, his assistants picked them up and carried them inside. Next Shabbos, they wanted to carry them in again, but he forbade them, because it was as if the people knew.
עירובין מד ע”ב: כאן לדעת, כאן שלא מדעת… הנהו זיקי דהוה שדיין בריסתקא דמחוזא, בהדי דאתא רבא מפירקיה אעלינהו ניהליה. לשבתא אחריתי בעי עיילינהו. ־ ואסר להו, דהוה ליה כלדעת, ואסור.
The Gerrer Rebbe once left a rare sefer in shul, and on Shabbos he wished to bring it home. So he told his gabbaim to announce that he would be walking home at a certain time. The Chassidim came to greet him, forming two lines along the street. The Rebbe, with the sefer hidden in his pocket, walked between the lines all the way to his house.
Source: R’ Eli Stefansky
Read and Remember 