When a word sounds exactly the same in French as it does in English, yet has an entirely different meaning, it is often referred to as a ‘False Friend’. Indeed some words can have a meaning far removed from what you intend.
For example a ‘chauvinist’ in French means ‘nationalist’ in English.
It is for this reason that no pubs or bars, serving great food, in France are referred to as ‘gastros’, because while in the UK the word might conjure up connotations of exquisite gastronomy, in France the exact opposite is the case.
To say you had a ‘gastro’ at the weekend is to imply that you had something approaching gastroenteritis i.e. diarrhoea, vomiting or both.
So before you take any of your French friends to a ‘gastro-pub’ in the UK, make sure to explain the meaning of the word first!