Usually when one mentions orange juice in a cocktail, it is referring to the fresh orange juice in a carton. These typically come in two varieties: either orange juice with bits, or without bits. It all depends on your particular preference when it comes to this, but it really does not matter which you choose. Cocktails often taste better when the orange juice has been left in the fridge for a considerable amount of time, so that it's nicely chilled. Buck's Fizz – or what the Americans refer to as a Mimosa, is perhaps the most famous cocktail to contain a drop of orange juice. Although other famous cocktails that contain it are the Sex on the Beach and and the Screwdriver cocktails.
As a footnote, it is important when buying your fresh orange juice, that it is actually fresh. Some brands of orange juice have a tendency to try and trick consumers into buying what they believe is 100% fresh orange juice, when in fact it's 100% quality, for example, with the quality being in a smaller font than the 100%. Be careful!