Drag queen eyebrows are eyebrows that have been massively overplucked. They are not only seen on drag queens - they could just as easily be called trailer trash eyebrows or stripper eyebrows.
This is typically seen on people who wear a lot of makeup. Plucking the eyebrows down to a very thin line allows those not gifted with a naturally graceful and feminine curve of eyebrow hair to easily paint on eyebrows in the desired shape. For drag queens, strippers, and other performers for whom a beautiful, feminine face defines their success, plucked eyebrows are almost a necessity. This is especially true for drag queens, since men and women can have such differently shaped eyebrows.
When the wearer has not applied fake brows with makeup, drag queen eyebrows look like a pencil-thin arc above the eye. The rounded shape makes the wearer look sort of like a surprised alien.
Unfortunately, it's also somewhat common to see drag queen eyebrows on white trash teenagers who haven't learned to pluck their brows properly. Even more unfortunate is that they tend not to be fastidious about plucking them, so that you get a thin arc of eyebrow and below it, an array of errant hairs shooting off in all directions.
Eyebrow hair has a notorious tendency not to grow back, so it's probably best to only experiment with drag queen eyebrows if you're doing it for the good of your career.