A very popular drink here is avena, which is the same word used for oatmeal but here if someone offering you una avena, they mean the drink!
It’s composed of oats, milk, water, sugar or honey and cinnamon and sometimes nutmeg. This is mixed together then heated-up in a pot. It’s then cooled-off and refrigerated. Finally it’s put in a blender and served cold, sometimes with ice cubes. It looks a bit like Mexican horchata, which uses rice.
Before you go yech, try it. Like many things, it may sound weird but it’s really nothing gross and you might just love it, and it’s a healthy drink! Taste is 100% a personal thing.
Sidenote: you can also buy it in grocery stores, but it doesn’t compare to fresh made.
If you want to make it at home here’s a recipe (link checked for malware): https://www.mycolombianrecipes.com/avena-drink-avena…/