I think they may have been interested in both being able to enjoy a fresh sandwich and intergalactic domination and Tupperware parties were all part of their plan to conquer the Earth. A few years ago they launched a massive Tupperware Party invasion, but for some reason their whole plan collapsed, some military historians claim that the invasion failed due to logistical supply problems. But we'll never know because the government's report on the incident are still classified as Top Secret.