There are often fragrance ads placarding the walls of the Parisian métro, which is nothing surprising in a city where a perfume of some sort, be it an eau de cologne or a niche fragrance, can be found every few steps. Really, you can canvas a given area and realize how many opportunities you have of purchasing a bottled scent in groceries, pharmacies, clothing stores and perfumeries. Even at one point at the postal office.
This morning however, there was a different kind of advert hovering above the heads of passengers in the cars in the métro aimed at extoling the virtues of functional perfumery. Instead of the usual aspirational, deluxe advert, you had an olfactory ad making a joke by relying on a word-play to praise the merits of using anti-bacterial soft soap...
The tag line reads "Pour vous ça sent la mandarine. Pour les bactéries, ça sent le sapin."
Literally this means "To you it smells of mandarin. To bacteria, it smells of fir-tree." What it really means is that the users of the soft soap by household name Le Petit Marseillais will have the pleasure of smelling the scent of mandarin when pressing on the pump while the bacteria themselves will smell their death approaching.
"Sentir le sapin" is an expression in French which can be applied uncharitably to older people to stress their age and imply that they are so old as to evoke the proximity in time of death. It can more generally be used for people of all ages to say that there is a danger of death. The scent of fir-tree refers to the custom of making coffins out of fir-tree wood.
The funny part is in the layered nuances contained in the expression "ça sent le sapin". It conjures up a tone, a sense of personal conviction, a nuance of anxiety, an archetypal average French person's mentality, a dose of flair and intuition, a sense of nervosity, an inverted expression of passion for life, a nuance of intellectual clarity, a propensity towards pessimism, a sense of definitive superiority and authority.