Mars Dilemma - S1.E7

Ned is sent to the grocery store to get a can of tomato paste, but Newton instead suggests they go to Mars, thinking that it's made of tomato paste similar to the idea that the Moon is made of green cheese. They go to Mars, and it is made of tomato paste! But they find that the tomato paste there tastes awful, so they decide to just get it from the grocery store after all.