They kinda look like bananas, but they also look like fat sausages. Maybe they should put them in a hot dog bun or roll for their next promotion.
As you can see, the promotion comes complete with a silly-looking monkey mascot.
The donuts comes in four flavors: Banana (of course), Green Apple, Strawberry, and Chocolate. Described as "chewy," the Monkey Bananas appear to be a type of cake donut possibly with glutinous rice flour somewhere in there for that chewy texture. They're also about the size of a mini banana; about 2 to 3 inches long it looks like.
You can check out a cross section of the donuts here:
For reference, here are some mini bananas: