"Now? This late?"
"Yeah. I need to give someone a ride home."
"Daaaadddd. Please!" (Dad, being ever-clueless, succumbs reluctantly).
"Sure, go ahead."
Seems the last day of finals was today. Dad put 2 and 2 together. Friend likely blasted at party. Son has auditions for college tomorrow, hence is sober.
Best decision I ever made.