Sot-l'y-laisse

sot / sotte = silly (the 't' is silent in the masculine form)
e.g. petit sot! = you silly thing!
un sot-l'y-laisse = a chicken oyster. Literally, it means "the part that a silly person would leave behind"

Barbe à papa

une barbe = a beard

E.g. se laisser pousser la barbe = to grow a beard
barbe à papa = cotton candy (literally daddy's beard)


Barbapapa is also the name of a series of children's books and cartoons born in France in the 70s, featuring a pinkish blob called Barbapapa and his wife Barbamama.

OVNI

OVNI stands for Objet Volant Non-Identifié, where:
un objet = an object 9the final 't' is silent)
volant / volante = flying. As a noun, un volant = a steering wheel
non-identifié(e) = unidentified

As you must have guessed by now, OVNI is the French acronym equivalent to UFO. In news today, France became the first country to open up its UFO files to the public. If you have an investigating mind, or would like to practice your French by reading transcripts of police interviews of farmers who claim they were abducted by aliens, you can do so on this site (at the time I'm writing this, however, it is down. I suppose too many UFO investigators tried it out).

Cream

First, let's start with the less obvious usage, as a masculine noun:
un crème = an espresso with milk



And now for the more usual one:
la crème = cream

For example:

• fraises à la crème = strawberries and cream
• la crème anglaise = custard ("English cream")
• la crème de la crème = the crème de la crème, the very best
• crème fraîche = heavy cream, or crème fraîche, since it recently officially made it as an English word according to the Oxford dictionary (thanks Fredrik)
• crème Chantilly = Chantilly cream
• crème fouettée = whipped cream
• crème brûlée = crème brûlée ("Burnt cream")

and a lot more...

La relégation

reléguer = to relegate, to banish

E.g.: reléguer quelquechose au second plan = to push somthing into the background
in sports, la relégation is, well relegation, i.e. what is looking more and more likely to happen to Paris' laughable soccer team, Paris Saint Germain

RAS

signaler = to point out, to report, to indicate something, to remind

E.g.:

• je te signale que tu parles à ta mère = may I remind you that you're speaking with your mother
• je leur ai signalé qu'on serait en retard = I let them know we'd be late
• rien à signaler = nothing to report (abbreviated RAS)

Raaaah

râler = to moan/groan/complain
E.g. qu'est-ce que t'as encore à râler? = what are you moaning about now?
un râleur / une râleuse = someone who complains a lot
un râle = a groan
râlant / râlante (adjective) = infuriating

Bitters

aigre = sour (works for both masculine and feminine)
doux (feminine: douce) = sweet (the 'x' is silent)

aigre-doux = bittersweet