Talking of Blondes...
A young blonde lady had the windows in her house replaced with new, double insulated, energy efficient windows. Twelve months later, she gets an irate call from the contractor complaining that the work has been done for a year and, despite repeated bills and dunning notices, she has yet to make the first payment.
The blonde replies, "Now don't try to pull a fast one on me. The salesman who sold me those, told me that in one year, they would pay for themselves."