Expression du jour

un four (pronounced foor) = an oven / furnace
un moulin (pronounced moo - lin) = a mill

on ne peut être à la fois au four et au moulin = one can't be in two places at once (literally you can't be at the furnace and the mill at the same time)
apporter de l'eau au moulin de quelqu'un = to fuel someone's arguments (literally to bring water to one's mill)