Floored

If you are 'floored' by something, it means you are shocked and can't believe what you're hearing.

Example:
-I can't believe you didn't get the job! I'm just floored!
-Yeah, me, neither. I'm still in shock.

Full of shit

Someone who is 'full of shit,' is someone who is completely lying. Since 'shit' is a bad word, obviously this should only be said around people with whom you have a close relationship.

Example:
-I can't believe she actually said that! She's so full of shit!
-Totally!

Friends with benefits

If people are 'friends with benefits,' it means they are friends who have sex. This implies that there are no strings attached -- neither person intends to get involved romantically. They're friends, but that's it. Well, except for the sex part. The problem with this is that one person usually ends up having feelings for the other, and that usually ends things pretty quickly.

Example:
-So are you two going out, or what?
-Nah! Just friends with benefits!

Feeling out of sorts

If you're 'feeling out of sorts,' it means that you're not quite feeling like yourself. You feel a little off, and perhaps a little sad.

Example:
-How are you feeling today?
-Well, I'm a little out of sorts. I'm not sure what's bothering me.

Fender bender

A 'fender bender' is a minor car accident where someone bumps into another car and causes a small amount of damage. Now that fenders, now called bumpers, are painted the same color as the rest of the car, instead of being black like they used to be, even a little fender bender can be quite expensive to fix.

Example:
-Yesterday I had a little fender bender!
-Did you do any damage to the other guy's car?
-No, just to mine!

Fighting words

'Fighting words' are words that someone says that could easily start a fight. Sometimes the person using them does so on purpose out of hate, and sometimes it is just out of pure ignorance.

Example:
-When I was a kid, a boy calling another boy 'gay' was fighting words.
-Yeah, people are more tolerant than they used to be.

Free refills

A 'free refill' is what you get when you're at a restaurant and the server refills your drink free of charge. They are common in chain restaurants, but not as much in smaller, local restaurants.

Example:
-Would you like some more Coke?
-Do you have free refills?
-Yes, we do.
-Then, yes, please!