The House of Commons broke into cheers and laughter Monday after NDP Leader Jack Layton dropped the first letter from the word gas.

Layton was pressing Prime Minister Stephen Harper to cut subsidies to big gas producers, but misspoke.

Layton had a look of conviction as he launched into his stumble, but after a few seconds of parliamentary laughter, he grinned at his own mistake.

The PM said he hoped the NDP leader didn't mean Harper personally with his reference, and then fed the flames by saying that "I promise to get to the bottom of it."

The NDP has estimated that oil and gas companies get tax breaks worth billions of dollars. The party's policy says ending the subsidies to companies making record profits would improve the environment.

Harper said the government has introduced a bill to clean up the environment.