It's wrong to leave your friends behind.
Dave drove his friend Jack to a bar downtown, but Dave is not having a good time, while Jack is.
Dave wants to go home.
Dave tells Jack that he's going to leave after Jack has one more drink.
Dave leaves the bar while Jack is in the bathroom and drives home.
Jack goes home with Dave after one more drink and then buys him gas as thanks for taking him out.
Jack has no ride home and has to spend $40 on a cab.