Apparently it's offensive to women.
The ad features a 1969 print called "Hi-Ho, Silver," which shows a young woman in a cowboy hat and skirt straddling a fence. The caption says: "Still on the fence?" and encourages farmers to choose the wheat board for marketing grain.
Read more: Canadian Wheat Board
Read more: Canadian Wheat Board
I guess these people have never seen a bull have it's sphincter tickled.