There's also a one touch empty dirt cup that means you don't have to get your hands dirty while you're cleaning it out after use. (geekwrapped.com)
I remember dirt cups from dirt cake from my kindergarten days, oh how I loved them... I love everything going on in these cupcakes, what a good idea! (veggieandthebeastfeast.com)
One thing that really stands out about it is the large 1 liter dirt cup. (geekwrapped.com)