Just use the gravity gun until they get the hint.

Not a very good zen garden.

NASCAR is such a retarded sport that even an insect can do it.

Fantastic.
We had loads of these at my grandparents' house when I was younger. I used to catch ants and flick them haplessly into the pits, then watch as it slowly slid into the middle, and was dragged a la' Tremors under the sand.
For one summer, I was heaven, I was hell, I was god of the ants.

Sim Ant has made me eternally hate these things.