The Sunnyboy was a popular Australian brand of flavoured ice block, well known for its distinctive tetrahedral shape (a design called a tetra-pak), sold individually or in packs. The ice blocks were extremely popular all the way through to the early 1990s, being cheaply available throughout tuckshops, discount stores and milk bars across most Australian states.

In 1980, the Australian rock band the Sunnyboys were established, with the ice block as their namesake, to represent "bright, happy, young, fun". In March 2013, comedian Dave O'Neil suggested that the company could ask the Sunnyboys to rename their band to one of their more marketable food product lines.

The Berri Co-operative Packing Union started in the town of Berri, in the River land region of South Australia in 1943. In 1961 a separate company, Berri Fruit Juices Co-operative Ltd was established. The Sunny-boy trademark (with its original hyphen) was first registered by Berri Limited in 1964.

There were three flavours originally: orange (Sunny-boy), raspberry (Razz), and cola (Glug).

They were relaunched in the 1990s and all were called Sunnyboys with flavours like Orange Explosion (or original 'Sunnyboy'), Razz Raspberry, Zap Lime, Pow Pine Lime, Glug Cola, and Lemonade Blast.

In October 1996, Buzz Blackcurrant flavour was introduced.

The vigorous nature of the packaging design meant that eating the ice block could take an entire school lunchbreak, and was difficult on the teeth. Charlotte Willis noted that the Tetra packaging had to be cut at just the right angle in order to be opened, and that the shape meant they were easily dropped. The equilateral triangle pack was changed to an isosceles shape in 1987.

An instant-win competition meant that every "one in five" ice blocks had a giveaway offer, with the prize of a subsequent free Sunnyboy, commonly referred to as “a free”, or 'lucky'.