Complex sentence: It is a popular tradition to receive a yard glass as a gift for coming of age celebrations on one's 21st birthday in Australia as well as in New Zealand, where it is often referred to as "doing a yardy".
Split into simpler sentences: It is a popular tradition to receive a yard glass as a gift for coming of age celebrations on one's 21st birthday in Australia as well as in New Zealand. In New Zealand, drinking a yard is often referred to as "doing a yardy".