Cream whippers are a great way to add flavourings to alcohol. Cream whippers work by using small chargers filled with compressed nitrous oxide to aerate the liquid of your choice, and force it through a nozzle at the top. The chargers of nitrous oxide are small metal cartridges that need to be slipped into the sleeve of the canister. The sleeve is then carefully screwed into the side of the canister until the gas is released. When the trigger or lever is pressed in, the compressed gas mixes with the liquid to produce a foam.