South Park, Season 11

Homeless Advisor:
They feed on our change. They need it in order to keep them moving.

Bum 14:
Is that...is that some spare change?

Homeless Advisor:
Somehow they're able to take our change and turn it into nourishment, sustenance.

Bum 14:
Spare some of that change, sir?

Homeless Advisor:
But now watch. [drops some coins into the bum's cup and walks back to the boys; the bum rattles his cup a bit]

Bum 14:
Spare some change?

Homeless Advisor:
It has already completely forgotten that I've given it change. It just wants more, change. Look over here. [heads to his left and the boys follow] This one I've kept deprived of change for over three days.

Bum 15:
Chaaaaange?

Kyle:
What's it doing?

Homeless Advisor:
It's dying.

Cartman:
Cool.