This post will mean little to you if you don't speak French. But I can't help myself. In six months my french has improved a lot. I've gotten much better at grammar and have extended my vocabulary. But not all the words I learned are necessarily appropriate. The French use a lot of slang. Here's some of what I've learned! Try to stay with me :)
Putain de merde- Just realized I maybe shouldn't have started with this one... it's gros mots/swear words.
Trop classe- So class, so nice. It can be used to describe clothes, a place, anything that is impressive.
Tu m’etonnes- Literally this translates to "you surprise me" but it actually means "no duh" or "obviously".
C’est pas terrible-Likewise, you would think this means "it's not terrible" but it actually implies that things are terrible! For example, a 6/20 on a test is pas terrible!
Je kiff- Kiffer means to love something. Je kiff ce jeu-I love this game.
Tu fais chier- You're annoying, but much meaner than that!
Verlan- This is going to sound crazy but the French like to talk backwards. Verlan is the French version of pig latin, except it's actively spoken. It is words in reverse or with mixed up syllables.
The name verlan is itself in verlan as it comes from a l'envers (reversed). The most commonly used word in verlan is meuf, which comes from femme (woman).
Understanding French is enough of a challenge for exchange students, now we have to know it backwards too!