Burn one off
To set fire to ones flatulent gassy fart. Can be done alone or as a party piece. If done with a crowd of mates a competitive element may arise to see who can burn off the longest flame.
Example:
"Quick, Lend me your lighter" said Andrew, "I've been on the baked beans, sprouts and Guinness again so stand well back while I burn one off".
"Quick, Lend me your lighter" said Andrew, "I've been on the baked beans, sprouts and Guinness again so stand well back while I burn one off".