My elementary school librarian always told my class, “You can’t judge a book by its cover.”

Actually, a lot of older people told me that. But old people die, and so do their phrases. So move over, Grandma and Grandpa’s metaphorical lesson about superficial judgments; it’s time to teach the kids a more updated version of this phrase:

“Don’t judge people until you’ve heard their ringtone.”

I was on the T during rush hour yesterday, when Journey’s “Don’t Stop Believin'” appeared to be playing from a large man’s butt. Was he an extraordinarily fantastic robot with a radio in his metal gluteus maximus and an unshakable desire for ’80s-monster- ballad bands?

No, unfortunately. He was just a huge, 6-foot-6 man dressed in a baggy Celtics basketball tank top with matching shorts that went down to his ankles. “fly duds,” if you will. Truth be told, the Journey ringtone really threw me off. What do ringtones tell us about people? Do they reveal truths, hidden secrets or forsaken desires about one another, or just let us know that someone we may or may not wish to speak to is calling us?

For instance, let’s say a young businessman, on his first interview after graduating college, forgets to shut off his phone while riding in the elevator up to the office. Little does he know that the man next to him will be his future boss. When his phone starts playing “Beautiful” by Christina Aguilera, he panics and tries to shut it off before the important-looking guy hears it. Long story short, he’s surrounded by co-workers whistling and humming the song for the first six months of employment.

A ringtone tells a lot about a person. Let’s say a typical female student just hooked up with some guy, and everything seemed to be going pretty swell. She sees him walking ahead of her on the way to class, and decides to give him a call to tell him to turn around so they can lovingly frolic along Commonwealth Avenue. She faintly hears his phone ring as she awaits his voice.

It’s “Tomorrow” from the 1982-Broadway hit, Annie. That didn’t play when they were hooking up last night. Just her luck, another guy she made out with was probably gay.

Or perhaps you’ve got the hunch that your cute lab partner doesn’t know your name, even though you’ve been out — five times. He tells you to call his phone so he can show you the cool song it plays when you call.

You admire his dedication, pick up the phone and dial. Elvis Costello’s love song “Allison” plays as the male bimbo sways to the tune and wonders why your reaction is not lots of lovin’, but a look of pure confusion.

Your name is Ashley.

Or, you’re struggling to stay afloat in your physics class, so you go to the professor’s office hours for some help. He starts to explain some theories, when — bam — his phone starts to play Right Said Fred’s “I’m Too Sexy.” Talk about an awkward moment. You imagine him in the outfit the singer wears – you know the one: leather pants, mesh shirt and shaved head. Is he the Right Said Fred? Or is he just an old physics professor who enjoys early ’90s dance songs with homoerotic undertones?

Now imagine an altar boy is in church, carrying the cross to the altar. In the middle of the precession the entire congregation hears Charlie Daniels’s “The Devil Went Down to Georgia” over the sound of the organ. Needless to say, the boy was never planning on entering the priesthood and now definitely never will.

You also have to be careful about people with tricky ringtones. Just like the gangsta on the T whose ringtone threw off his toughness, a ringtone can also support the local crime scene.

For example, you’re sitting on the T when a young man sitting next to you takes out his phone as it plays “Kumbaya.” What a peaceful person.

No way, José. You’re susceptible to theft because his ringtone influences your belief that he’s a peaceful, religious young man. He steals your bag, though, as you tie your shoe, and is grateful his $1.99 ringtone helped his bad habits once again.

It’s pretty difficult in this day and age not to judge people by their ringtone. A book may not choose its cover, but people sure do pick their ringtones.

Megan Murphy, a sophomore in the School of Education, is a columnist for The Daily Free Press. She can be reached at [email protected]