A dumb blonde goes to an electronics store...

...And sees a sign on the front of the store that says "No dumb blondes". Believing she isn't dumb she goes in and asks the man at the counter if she can by one of the televisions that are right behind him. He says no you're a dumb blonde, please leave. So the blonde decides to dye her hair brown and goes back into the store the next day to try and buy the tv. At the counter the man again says that she is a dumb blonde and she needs to leave. So once more the blonde dyes her hair and go to the store, this time with red hair. She gets to the counter and the man again denies her claiming she Is a dumb blonde. Frustrated she exclaims to the man "I've dyed my hair twice to try and fool you so you would let me buy that tv! How could you tell It was me the whole time?" The man then tells her "Because that's not a tv, it's a microwave."