No? How about with doughnuts?
In Palm Beach, Fla., reports the Palm Beach Post, the three local Krispy Kreme stores are giving students in kindergarten through sixth grade a free doughnut for every A on their report card, limited to six each grading period. This is despite a local charity push, spearheaded by the Robert Wood Johnson Foundation, to spend $1.4 M in area schools to fight childhood obesity and promote healthier lifestyles.
The best stat is in the online poll accompanying the story, in which 56% of the respondents say about the doughnut giveaway "It's great. It's a harmless incentive for reaching a goal."