"It is my birthday"

A young boy and his grandfather go out on the young boy's birthday. Let's call the boy Jim and his grandfather John.
Jim:"Can we go to the park?"
John:"What's wrong with staying at home?"
Jim:"Come on. It is my birthday"
John:"Oh. Go on then."
They go to the park.
Jim:"Can I get an ice cream?"
John:"An ice cream? I've already taken you out to the park."
Jim:"Come on. It is my birthday"
John:"Alright. Seeing as it is your birthday.."
He gets the ice cream.
Jim:"Can I have a ride on the donkeys?"
John:"What? I've already taken you to the park and gotten you an ice cream."
Jim:"Come on. It is my birthday"
John:"Ok. Let's go on 'em."
He rides the donkeys.
Jim:"Can we take the donkey home?"
John:"Take the donkey home? I've already taken you to the park, gotten you an ice cream and let you ride the donkeys."
Jim:"Come on. It is my birthday"
John:"Oh for God's sakes; alright!"
He takes the donkey and starts walking home.
Jim:"Can I name the donkey?"
John:"Yeah, if you want."
Jim:"I want to call it wanker!"
John:"WHAT? Ok, ok. Just don't tell your nan."
Jim:"Ok."
That night Jim ties the donkey up to the tree. Jim wakes up to a storm raging outside. The donkey is running around like mad and after a huge show breaks free from the rope and starts to run off.

Jim runs as fast as he can into John's room and shouts:
"GRANDAD! Wanker's off! Wanker's off!"
John:"Now listen here, son-"


Edit 1: Sorry for poor layout. Written on mobile.