Passing gas is a normal body function, while it may not be polite to do in public, you wouldn't expect to be fined for it.
A man in Vienna was charged €500 ($564) for passing gas at police earlier this month. The department took to Twitter to clarify the situation, according to BBC saying that "of course no-one will be reported for accidentally 'letting one go' once." The department continued on to say that when the man was first approached by police, he was uncooperative, and then rose from the park bench and "looked at the officers and apparently intentionally released a massive intestinal wind in the immediate vicinity of the officers."