Microwaving popcorn on cob in brown paper lunch bag works fine. Position the cob in bag so both are standing upright. Timing is oven dependent. Some popped corn will remain attached to cob. You should avoid paper bags labeled as having postconsumer recycled paper due to possible metal fragments just as you should avoid using paper towels with recycled paper in the microwave.
We were given a fairly good-sized package of popcorn on the cob several years ago and so have some experience. Since then, we have bought popcorn on the cob at farmers markets occasionally. The ornamental little ears of strawberry corn are a form of popcorn but have a relatively low expansion ratio when popped. Some but not all of the small-eared ornamental corns are popcorn. I wouldn't buy any of these strictly for popping, but it can be neat way to use them once fall decorations are set aside for Christmas decorations. I would rather eat the corn than feed it to squirrels.