Despedirse a la francesa
No significa despedirse con besos, sino irse de un lugar sin despedirse del anfitrión o amigos.
En Francia, en el siglo XVIII era una manera de mostrar que uno se lo estaba pasando bien en una fiesta. Si no se despedía se daba a entender que iba a regresar a la fiesta. Pero al pasar al inglés y al español pasó a tener una connotación negativa.
To take a French leave
If you don’t know what it means, you could suppose it means to say goodbye with two or three kisses on the cheeks, although that is a nice thought it’s not the real meaning of what lies behind this fabulous saying.
It has been heard in the UK, not as well known in the states. It means to leave a party without saying goodbye. This custom arose in the 18th centurty in France, it is said to have been a compliment in the day between nobles as it was implied that if you did not say goodbye you would return to the party and thus you were enjoying yourself.
However, as it was passed on to both English and Spanish it entails a rather negative connotation and implies rudness.