They are brainwashed at FishCamp, which their parents attend
Woe be unto the kid whose parents don't buy into the "traditions" of Aggies, complete with Milk Men, swaying, "whooping" (reserved for seniors and graduates only), "squeezing", among other things. Students are ostracized.
The one thing the Aggies do right is Muster. If you haven't been or observed, last year's was done online, and I think is available on YouTube. Ross Volunteers at their finest. The precision is unbelievable.
Although it requires special permission, I have had the honor of attending Muster and answering for my best friend, who had passed two months before.