The Art Of Decept ... Errr ... Persuasion
Dolinski found that people were more likely to mind the woman's grocery cart when they had been previously asked to fulfill an unusual request — to tie someone else's shoelaces.
(Source: NPR, Tie My Shoes, Please: How Persuasion Works)
I remember the door-in-the-face technique being used on residents in the Bay Area a few years back.
"We're going to hike the bridge tolls to $10!" (From $3 or $4.)
"At least it's not $10!"