When Beta Theta Pi first arrived, one of my sisters say the guys wearing letters. From a distance the theta looked like an O so she called them BOP like TEP. The guys said that no one called them BOP at any other chapter, but we liked it so it stuck.
When I was a freshman pledge, a woman from one of my classes who knew nothing about greeklife asked me why some many women were wearing eat across their chests. I had no idea what she meant until she pointed and said there's another one. She thought that SDT looked like EAT.