a blonde and a "big screen tv"

a blonde walked into a store and asked a clerk "can i buy that big screen tv?" and the clerk said "sorry mam we dont sell things to dumb blondes" so she leaves the next day she dies her hair brown and walks in the store and ask the clerk "can i buy that big screen tv?" then the clerk said "sorry mam we dont sell things to dumb blondes" then the next day she dies her hair red and walks in the store and ask the clerk "can i buy that big screen tv?" then the clerk said "sorry mam we dont sell things to dumb blondes and by the way mam that isnt a big screen tv its a microwave"