Sitting shotgun American -ing form verb
Jade has been driving for five hours; we need to change the driver; let him sit shotgun and take a nap.
Jane got to sit shotgun this morning. it's my turn now!
let's get in the car! Who wants to sit shotgun?
In squatting position
Starting of the idiom is a verb, we need to conjugate tense for the verb.
This expression is an allusion to the guard who rode alongside a stagecoach driver, ready to use his shotgun to ward off bandits or hostile Native Americans. In modern use, it implies the practice of sitting alongside the driver in a moving vehicle.
Source: internet