when people say "you will know"

Has anyone heard stories from women that they didn't even realize they were in labor until they told someone their back kinda hurt every 5 minutes, and that person told them to go to the hospital, and then, bam!  baby born!  
I've heard this same story from 3 different women- one of them my mother- and it kinda scares me.  When I share that I'm afraid of that happening to me I get laughed at and told "oh, YOU'LL KNOW!"  
Do you think the women that tell these "I didn't even realize I was in labor" are just embellishing and trying to sound tough?  
I'm getting contractions every 15 minutes or so.  I'm pretty sure they're not Braxton hicks because they don't ease up and I can feel them in my lower back and down the inside of the thighs.  They just don't hurt that bad.  Like on a scale of 1-10 maybe a 2.5.  I imagine that they will suddenly get much worse.  I mean IT IS labor... it's painful right??!