When the av bet din (who was second in importance) entered, two rows would stand up on either side of him, and would remain standing until he reached his seat.
When the hakham (the third in importance) entered, the students would stand up when he passed by and immediately return to their seats.
Rabbi Yohanan explains that this was established during Rabban Shimon ben Gamliel’s term in office, when he was the nasi, Rabbi Me’ir was the hakham and Rabbi Natan was the av bet din. Originally the students stood up before all, but Rabban Shimon ben Gamliel was disturbed that the position of nasi was not given special recognition, so he instituted the above practice on a day that neither Rabbi Me’ir nor Rabbi Natan was there. When they learned of the change in procedure, they conspired to rectify matters.
The Gemara relates that Rabbi Me’ir suggested to Rabbi Natan that they ask Rabban Shimon ben Gamliel to teach Masechet Uktzin – a small set of Mishnayot at the end of Seder Taharot that does not have Talmudic discussions on it in either the Jerusalem or Babylonian Talmud. Since he is unfamiliar with it – after the destruction of the Temple, the study of ritual purity lagged and even a scholar like Rabban Shimon ben Gamliel was not expert in it – we will step forward and proclaim that he is unworthy to be nasi, and we will move up in our positions.
One of the students, Rabbi Yaakov ben Korshai, heard this discussion and was concerned lest it lead to the public humiliation of the nasi, so he sat down behind Rabbi Shimon and reviewed the material aloud. Hearing laws of purity with which he was unfamiliar, Rabbi Shimon committed them to memory and successfully taught them when challenged to do so by Rabbi Me’ir and Rabbi Natan. Recognizing the attempt at mutiny, Rabbi Shimon then commanded that they be removed from the bet midrash.
Ultimately it became clear that the students turned to Rabbi Me’ir and Rabbi Natan for advice and direction even while they were exiled from the bet midrash, so Rabban Shimon ben Gamliel consented to allow them to return, but as punishment they lost the right to have their teachings ascribed to them. Rabbi Me’ir’s teachings were to be recorded as the words of aherim “others,” while Rabbi Natan’s teachings were recorded as yesh omrim “some say.”
The Bet Shmuel explains Rabbi Me’ir’s epithet as indicating that he started the plan and others followed his suggestion. In his Meromei Sadeh the Netziv points out that it carries with it an oblique reference to the fact that Rabbi Me’ir was a student of the disgraced tanna, Elisha ben Avuya, who was called Aher.
Ben Yehoyada argues that Rabbi Me’ir and Rabbi Natan were not planning to undermine Rabban Shimon ben Gamliel’s position on a permanent basis, rather they wanted him to recognize the embarrassment of changing the norms and protocols of honor in the bet midrash.