To do something in a bold and no holds barred way.
I saw this cute girl in a coffee shop, so I talked to her and got her number, shotgun style.
The act of a male masturbating in the front passenger seat of a female's car, in the hope that she will join him. Usually a last act of desperation on an unsuccessful first date.
"My friend Nika went on a first date with this guy and he totally shotgun styled her at the end of the night".