Subway

Last Sunday after the church service, my little brother Josh inquired if our family could eat out at subway for lunch. The ensuing conversation became quite complicated and ended in a very funny manner.
JOSH: Mom, can we go to subway?
MOM: No, Josh, because it would cost about $40.
JOSH: No it wouldn't. It would only cost $20 dollars 'cause footlongs are only $5 each. And you and I could split one.
MOM: I don't understand.
CHRISTI: Yah. It'd be $20 'cause it would be $15 for Dad, John, and me and then $5 more dollars for you and Josh.
MOM: What?
JOHN: Okay. Dad would get a footlong for $5; Christi would get a footlong for $5 (that equals $10); I would get a footlong for $5 (that equals $15); and then you and Josh would split a footlong for $5, so altogether it would come to $20.
MOM: Oh.... Are you sure that the footlongs are only $5 each?
And right after that question escaped my mother's lips, we drove up beside a bus with this subway advertisement on the side:


All I can say is that our van was filled with laughter for quite some time after that...