Today's thread is...
Leaving a 24 hour diner you notice a young (presumably) homeless man sitting by a sign holding a sign that offers a fantastic tale for just $1. He notices you scoff slightly, and says "It's a true story." As you walk past he adds "And you're in it."
There's the thread, a frame tale or merely leading into an interesting exchange, there is definitely an opportunity for some slipstream or magic realism if that sounds interesting, or maybe it's someone from your narrator's past that they no longer recognize. Many ways to run with this.
Aside from the prompt, here is a place where you can donate to help the homeless it's called the National Alliance to End Homelessness, it has a very low overhead and every little bit helps.