Hey bro, what's up? - This is a common greeting among friends.
I'm feeling under the weather today. - Means not feeling well.
That's a piece of cake! - Means something is very easy.
Let's hit the road. - Means it's time to leave.
She's a social butterfly. - Describes someone who is very sociable.
The meeting was a total train wreck. - Means the meeting was a complete disaster.