I KNEW somebody would catch my joke :P

I once asked a woman who was waiting at the same location to pick up her child that I was waiting to pick up my brother if she could give me a jump start. I had the cables. She exited her van and said "I'm sorry, I can't, my battery won't hold a charge." I said "Well I guess it was kind of dumb to turn off your engine now wasn't it?" She diverted her eyes from me and walked off.