What does Boob Shotgun mean?

Boob Shotgun meaning in Urban Dictionary

When a couple of dudes tend to be hanging out and a hot woman walks in, a person might exclaim 'Boob Shotgun!'. This might be related to two different people walking to a car or truck and something phoning 'shotgun', consequently saying the traveler seat. Exclaiming 'boob shotgun' methods to phone dibs on a woman, specifically of the boobs.