I know certain GLOs would always give the same set of letters to their newly initiated members so you may see a whole bunch of AOPi girls with white shirts with red letters on and know they had just been initiated. ZTA on my campus had "chapter letters" and they were all the same.
As far as lavaliering, some groups have specific "sweetheart" songs, etc that can be used. I witnessed a TKE lavalier one of my sisters and he asked to come to one of our chapter meetings and we did a candlelight, only she didn't know it was for her, her roommate was also a Zeta and stole her candle to use. Her boyfriend blew out the candle from behind her and lavaliered her right there. Immediately after, his brothers came in, serenaded her, and then carried him out to throw him into the pond on campus. Tradition enough for ya?

It was really neat to watch, to say the least!