This may be an urban legend, but it was told to me in all sincerity:

During a drunken session a group of blokes were relating their worst sexual encounters.
One of them was gay and after much persuasion told the group of his worst.
This incident occurred when he was performing oral sex on his partner of the moment.
He was licking not sucking so you can tell where he performing the afore mentioned act.
Accidentally his partner broke wind.
Now that is a horrible occurrence for anyone to contemplate.
But the worst part was that a piece of undigested sweetcorn was propelled into our heroes mouth by the release of gas.
Sweetcorn soup has never been quite the same since I heard this tale.