A driving instructor, an adult that'll drive with you when you have your learners permit, and/ or anyone teaching you how to drive from the passenger seat.
Person A: Hey I heard you got your permit, lets go somewhere
Person B: Nah I can't, my mom won't be Shotgun Sensai.
Person A: Wanna go to the mall friday?
Person B: I can't, I have a lesson with my Shotgun Sensai.