True confession time - I can't recall any instance EVER where something I overheard made it into one of my novels. I love to people watch when I'm out and about and certainly I must have heard any number of clever, funny or OMG-worthy dialog from the real people of the world but...it just doesn't occur to me to jot down notes or even try to remember the bons mot. (Hmm, maybe I need to hang out in a different environment LOL?)
What I do is immediately drift off into imagining people's back story, or what's going to happen to them next, or how things would play out in a novel, so I'm not paying much attention to what they're saying. (If we ever encounter each other at a conference and you sense me crafting an epic novel around you, feel free to recall me to the reality of our actual conversation, ok?)
I do have one novel waiting to be written that's based on actual events and might possibly contain some quotes of things people truly said in the moment. The problem I'm having with writing this, I realized after some fits and starts, is that when I'm writing from reality, my day job brain kicks in and tries to stick too close to the entire reality. The little auditor in my head gets all huffy with my Creative Muse and refuses to let creative license or creative anything take over the narrative. "She didn't actually say that at this point in the week," snarls the auditor. "He went to the emergency room after the vision of the little boy and the dog, not before," he nags. "The Angel of Death didn't actually utter any words when you saw him..."
But if I'm ever going to tell this story, it has to be fictionalized and romance has to occur for the heroine (because trust me, in the real life story this would be based on, there was nothing close to romance). A few things need to be heightened for suspense and others probably need to be toned down. So I need more distance and time from the events, clearly. I wonder if that would happen to me if I tried hanging out in more eavesdropping-friendly spots for a while and then went to write the scenes? Would the inner auditor/critic get all huffy and stifle the creativity, as it has with my one and only based-on-real-events story?
Fortunately I mostly write Ancient Egyptian paranormals (and you can't use modern chitchat there or your editor and your Readers go whaaat did he just say????) or science fiction romance (where I guess I could use juicy things I overheard if I could remember them)...well, so my brain apparently is not wired to use overheard snippets so feel free to talk when I'm in the vicinity! (Which autocorrect tried to make "virginity" but that would be a whole other post.)