Eating a cookie causes sparkle particles to appear around you.

So, we all know cookies are worthless. They take too much effort to craft and don't fill enough hunger. But that's totally realistic. The reason we eat cookies in real life is because they taste good. So let's bring that to Minecraft. When eating a cookie, the green sparkles from trading with a villager appear around your head. This is a fun way to add an emote to Minecraft. Cookies should also take as long as sweet berries to eat. For those who want functionality, giving a cookie to a villager could improve your standing with them a little bit, and possibly give you a discount. One cookie per day per villager though, don't want them to be too full for their dinner.