Faux pas are very culture specific; what is considered good manners in one culture can be considered a horrible faux pas in another. For example, in America it is usually considered good manners to bring a bottle of wine when coming to someone's house for dinner. In France, however, this is considered insulting as it implies that the dinner-hosts are unable to provide their own good wine.
Using a bidet as a toilet is a faux pas which is common with first-time visitors to Europe.
See also: most common Wikipedia faux pas\n