Summer's here. Time for a cool treat. So, you grab a popsicle from the freezer. Ahh ... that's better. Until, out of nowhere, a sharp sudden pain rushes to your forehead. You've got brain freeze!We talk with neuroscientist Caroline Palavicino-Maggio about the science behind these short-lived cold-induced headaches. Plus, some listener mail. What are your daily science curiosities? Email the show at shortwave@npr.org.