burpless
adj.— «Researchers in Australia have received funding to develop more digestible feeds for cattle—“burpless” grass, in industry parlance—that result in less methane being produced as they are broken down in cows’ stomach(s).» —“Aussies cultivate ’burpless’ grass” by Peter Freed TerraPass (San Francisco, California) May 15, 2008. (source: Double-Tongued Dictionary)
“Burpless” has also been used to market cucumbers supposedly engineered to not induce gas in the consumer.
“Burpless” always struck me as funny — as Luke mentions, I know it’s supposed to mean that the cukes don’t induce gas, but it always suggested to me that the cukes themselves were burp-free.