Yes, you can put a mug in an air fryer. However, there are a few things to keep in mind. First, make sure that the mug is oven-safe. Second, preheat the air fryer to the desired temperature before adding the mug. Third, place the mug on the rack in the air fryer so that it is not touching the sides or bottom of the unit. Fourth, cook for the recommended time based on your recipe or according to package directions. Finally, allow the mug to cool slightly before removing it from the air fryer.