Find yourself craving Doritos or a chunk of cheese, then you can say you're peckish. If you're peckish, you're a tad hungry (not starving, but hungry enough to poke around the kitchen cabinets).
While the informal word peckish is more common in the UK, most people in North America will know what you mean if you say, "I'm feeling a little peckish — should we make some popcorn?" Some people wake up in the morning feeling peckish, while others don't feel like eating for a few hours. Peckish comes from the verb peck, which a bird does when it bites with its beak — it basically means "hungry enough to peck at some food."