My friend Jerry Pournelle originated the term is his Byte magazine column with his orchids and onions for vendor service, software and hardware picks and pans. Bixen (people who lurked on bix.com) picked it up and used militaristic modifiers like like "with three elephant garlic clusters" to describe particularly egregious vendor behaviour.

If you see no onion it means your browser does not support CSS style sheets and these icons will be invisble to you until you get a browser such as Opera that supports them.