Slice cucumbers into 1-inch chunks. Finely chop green bell pepper and cut red pepper into small, thin slices; set aside separately.
With a small teaspoon, scoop a bowl out of the top of each cucumber. Fill with ranch dressing (or plain yogurt/low-fat sour cream mixed with ranch seasoning).
Top edges of the cucumber with green peppers, making a wreath; use a few red pepper slices for the bow. (You may need to add a bit of ranch to help everything stick.)