Taradiddle is a noun that means a petty lie.
Jeremy Diddler was a character from an early 19th century play called Raising the Wind. From that we get the word diddle, which means to swindle. The significance of TARA added to the word is not clear, but we do know that a taradiddle is less lethal than a diddle.
Susan’s excuse about having to work on the day I needed her help annoyed me a little, but I soon forgave her. After all, an occasional taradiddle between friends is nothing to get enraged over.