ride shotgun
Idiom used here and there by Young People
To ride in the front passenger seat of a vehicle. To ride shotgun is the goal of the game "calling shotgun", where people try to claim this front seat first. Possibly derived from film depictions of stagecoaches, where the person riding next to the driver would carry a shotgun.
"Riley rode shotgun the last time we drove to the park; now, it's my turn!"
8 out of 9 English speakers have heard this