A two-compartment container in which the first compartment has an upper layer and a lower layer and contains a first component that is to be added to the second compartment. Above the first compartment is a dome that is bowed upward and is flexible. Attached to the dome is a cutting means. Depressing the dome by pushing downward on it lowers the cutting means so that either the lower layer only or both the upper and lower layer of the first compartment are cut by the cutting means, releasing the first component into the second compartment. The cutting means may be a simple puncturer, or in the case where the second compartment comprises a beverage container or the like, the cutting means may be part of a tubular wall surrounding the opening through which someone can drink the beverage.