Foster's Home for Imaginary Friends - Season 0 Episode 15 Pen Pal
Overview: Eduardo has a British penpal and Bloo is convinced that it's the Queen of England. He tries to make her his penpal instead by writing her a letter. Mac suggests to use Nancy, an English pen imaginary friend, but Bloo claims it'll make the letter "boring". Mac then suggests a care-package to make her really believe that Bloo cares. Bloo brings in a huge package, but it turns out the penpal was really Nancy. She claims the package is "boring" and she can only use it as a doorstop.