A Top Gun stall is a roller coaster inversion, and can only be featured on a multi-tracked roller coaster.
The element is essentially the exact same as a zero-g stall; the only difference is with what you can see, and it only works if the trains are dueling. To be a Top Gun stall, the dueling train would be upright on an airtime hill directly underneath the train that is performing a zero-g stall. The maneuver is meant to mimic the maneuver performed in the movie Top Gun.
This element is currently only on one roller coaster: Twisted Colossus, at Six Flags Magic Mountain. However, the park is constructing another roller coaster for the 2019 season called West Coast Racers that will also feature the Top Gun Stall.