The phrase 'Tickled Pink' is used to denote that someone is expressing delight.
Example of Use: “Dad was tickled pink when he found out we got him a puppy.”
The expression 'tickled pink' is derived from the 17th century meaning of 'tickle' which is to give pleasure or gratify. The first time the phrase itself was seen in print was in a 1910 piece published in the Illinois paper The Daily Review: “Grover Laudermilk was tickled pink over Kinsella’s move in buying him from St. Louis.” Because the expression was included in a newspaper article, it is supposed that the writer assumed readers would already be familiar with it, meaning it was probably a popular phrase before appearing in print.