So ... it's about 13 years ago, on a lazy Sunday afternoon. We're in a co-op housing project at the University of Waterloo. I live with 4 roommates on the top floor, the third. My roommate Ross and I are home, just hanging out, playing cards or blowing ectoplasm bubbles or whatever, when there's a knock at the door. Ross, all 6'3" of him, gets up and ambles to the door. There stands this really young kid, tiny and blond and scared-looking. He's got one of those laminated cards like dannye mentions above ... but he gets one look at Ross towering over him and he loses all memory of his pitch. He looks way, way up at Ross, and in this thin, reedy voice he stammers :
"Ch-Ch-Chocolate bar for b-brain disease?"
And so Ross looks down at him, and says very seriously:
"But I don't want brain disease!"
That's too much. The kid dissolves into a Niagara Falls of tears. Somehow we manage to hold ourselves together long enough to console the kid. We buy several bars from him, and send him back downstairs to his hidden adult controller in the lobby.
I don't think this kid ended up in sales.