A blonde woman goes into an electrical shop to buy a tv. She gets the attention of the sales assistant and says to him, 'I want to buy that tv'. He tells her, 'sorry we dont sell to blondes'. So she goes home and dyes her hair brunette. The next days she asks him again, and again he says, 'sorry we don’t sell to blondes'. So she goes home and dyes her hair red this time. She goes back the next day and asks him again, and once again he says, 'sorry we don’t sell to blondes'.
A little confused now the blonde woman asks him 'how do you know that I am blonde?'
He turns to the woman and says 'I know you’re blonde because that’s not a tv, its a microwave'