I Said Get On!

so the other day grandpa jones (names have been changed because i'm just not good with them) gets on his bicycle to go and pick up his four year old grandson james. this is a journey he's taken before and the trip to the school passes uneventfully. it's great exercise for grandpa jones. he's 77 and this keeps him young and chipper. he makes good time and gets to school as the kids are coming out of school. he spots his grandson coming towards him and waves to make sure that the little boy has seen him. the boy approaches and grandpa says "hey son, let's go."
"go where?" the boy looks a little confused.
"what do you mean, go where? did you just wake up? we're going home. get on the bike." the boy still looks a little lost.
"but who are you?"
"what do you mean, who am i? boy, i'm your grandpa now stop playing with me and get on." grandpa picks up the boy and puts him on the bar and they set off. the ride home is quiet - grandpa has to save his energy for the ride and it seems the boy still hasn't woken up because he looks dazed. it takes a while but they get home and grandma jones comes out onto the porch. as grandpa jones is helping the boy of the bike she shouts out,
"so who the heck is that and where's my grandson sam?"
"now that's funny. you know it's sam."
"sam? grandpa, you've got the wrong kid."
did i mention that grandpa jones has been sam's grandpa for four years? and that grandpa jones has picked sam up from school before. that james is no relation of sam's and apparently doesn't even look like him?

good confused man that grandpa jones is, he put james back on the bicycle and took him back to his waiting aunt and picked up the correct grandson but, people, i couldn't make this up if i tried.