The term 'Sing in Tyrolean Fashion' is referring to the traditional Alpine style of singing known as yodeling. Yodeling is a form of singing that involves rapidly changing between the chest and head voice, creating a melodic sound. It originated in the Swiss Alps and is now popular in many other parts of the world. Yodeling is often associated with Tyrolean culture, which is why it is referred to as 'singing in Tyrolean fashion'.