I stare at whiny, bratty kids that are begging their parents to buy them something, waiting for them to catch my eye contact.  And sometimes, when they do, I can see the heat of embarrassment spread across their little faces.  It's almost like they've had a serious, grown up, moment of clarity.  A moment of realization: Holy shit, I'm acting like such an asshole right now.  What is wrong with me?  And then, as if it were never there, it fades away.  They bury their shame into their mother's pant leg and move on to the next object of desire, never quite getting back to that original state of bratty hysteria. 

I also stare at crying babies in their strollers and try to coax them into distraction with stranger smiles.  It works, give it a go!