A blonde goes to the mall to buy a TV. She looks around at the selection and then asks for assistance.

"Hi, I would like to buy this TV." she says to the clerk.
"I'm sorry, but we don't sell to blondes." He replies.

Offended, the blonde leaves the store. The very next day she comes back to the same store and says to the clerk:
"Hi, I would like to buy this TV."
Once again he answer:
"I already told you, we don't sell to blondes!"

Upset the blonde leaves the store and goes to the barber. She dyes her hair dark brown and returns to the store for a third time the next day.
She says to the clerk:
"Hi, I would like to buy this TV."
"I'm sorry we don't sell to blondes."
"How do you know that I'm really a blonde?" She asks.
"Because what you're calling a TV is really a microwave."