Mardi gras (Shrove Tuesday, literally Fat Tuesday) is the last day before Carême (Lent) which starts on Mercredi des Cendres (Ash Wednesday). On that day, people are supposed to eat rich food before fasting, a religious ritual for Lent. Pancakes and pancake races are very popular on mardi gras in the UK. French people have their pancake tradition on la Chandeleur, the 2nd of February. The usual buns for Mardi gras, and the carnaval (carnival) season are: beignets, bugnes, merveilles and oreilletes. Almost each region has its own version of these fried and sugary treats. Besides food, another tradition during carnaval time is the parades. The most famous ones in France are le carnaval de Nice, le carnaval de Dunkerque and le carnaval vénitien d’Annecy. Everywhere cities, clubs and schools organise parades exhibiting masks, flowers, floats, flowers, colours, music, dances and balls.

Sayings:

Tomber / arriver comme mars en Carême.
Literally: to happen as Lent in March. To happen for sure.
Considering that Easter usually falls more or less in April, Carême (Lenten) definitely takes place in March. Mardi gras though, which is 40 days before Easter, falls more often in February.

Avoir une face de Carême.
Literally: to have a Lent face; to look pale. Honestly, how can you expect to look after cutting out nourishing food for days?

Grammar: Nouns ending in -al, such as carnaval, bal…♥

Nouns ending in -al don’t follow the usual rule when becoming plural. Instead of that s (les fêtes), they form their plural in -aux. 
Ex: Un cheval, des chevaux; un journal, des journaux…
Exceptions:  aval, bal, carnaval, chacal, corral, final, festival, récital, régal.
un carnaval coloré, des carnavals colorés, un bal populaire ; des bals populaires; un festival d’été, des festivals d’été…

NB: the same rule applies to the words ending in -eau: un drapeau ; des drapeaux.

Poetry: 

The carnival of Venice is one of the most famous. This Italian city creates a very scpecial atmosphere all year round, but the short days in March, the masks, the balls, the palaces, the gondolas, the myths and history related to Venice, contribute to make the carnival festival in Venice a very special experience. French writer and poet, Théophile Gautier (1811-1872) comes to the topic in his Variations sur le Carnaval De Venise:

Venise pour le bal s’habille.
De paillettes tout étoilé,
Scintille, fourmille et babille
Le carnaval bariolé.

Arlequin, nègre par son masque,
Serpent par ses mille couleurs,
Rosse d’une note fantasque
Cassandre son souffre-douleurs.

Battant de l’aile avec sa manche
Comme un pingouin sur un écueil,
Le blanc Pierrot, par une blanche,
Passe la tête et cligne l’oeil.

Le Docteur bolonais rabâche
Avec la basse aux sons traînés;
Polichinelle, qui se fâche,
Se trouve une croche pour nez.

Heurtant Trivelin qui se mouche
Avec un trille extravagant,
A Colombine Scaramouche
Rend son éventail ou son gant.

Sur une cadence se glisse
Un domino ne laissant voir
Qu’un malin regard en coulisse
Aux paupières de satin noir.

Ah! fine barbe de dentelle,
Que fait voler un souffle pur,
Cet arpège m’a dit : C’est elle !
Malgré tes réseaux, j’en suis sûr,

Et j’ai reconnu, rose et fraîche,
Sous l’affreux profil de carton,
Sa lèvre au fin duvet de pêche,
Et la mouche de son menton. 

Théophile Gautier – Émaux et Camées

Beautiful carnival in Venice, inviting characters of the Commedia dell’arte: Arlequin, Cassandre, Pirrot, le Docteur, Polichinelle, Trivelin, Colombine and Scaramouche. The Commedia dell’arte started to be popular in XVIth century in Italy, when actors started to wear masks on stage (inspired by the ancient carnival celebrations) and decided to be recognised as professionals, organised in troupes. They were used to mixing all kinds of dialects and variations of the language, in order to be understood everywhere and by everyone in Italy. The Commedia dell’arte was very popular in France, especially in the XVIIth century when it inspired most of the famous playwrights but a bit forgotten in XXth century, when Gautier pays tribute to it. Writing it in a poem, Gautier offers a stage to italian theater tradition in his french poetry modernity, mixing genres and cultural traditions; imitating the Commedia dell’arte’s way of functioning. Poetry wears the theater mask. Could there be a better definition of carnival?