"Oh go on, mum,
please. Everyone else has got one..."
Kids want stuff. Power Rangers,Teletubbies, Nike trainers anything and everything.
Pester power is a marketing term, used to describe the massive buying power of children, due to the influence their pestering has on their parents buying habits.
The idea is that rather than targeting the parent, you target the child, who does not have the money to buy a product himself but can nag his parents into making a purchase.