1. "Bet." It means you're in agreement with something. So kind of like saying "you bet," but without the word "you."
2. "Get a bag." No, it doesn't mean a bag of drugs. It means a bag of money. If you "get a bag," you're talking about getting paid or coming into money somehow.
3. "No cap." It's basically the same as saying, "no lie." Like if you tack it on to the end of a sentence, you're just confirming that you're being serious, not joking.
4. "Out of pocket." It's not like "out of pocket" expenses. It means out of control. So if your friend does something crazy, you might say they're "out of pocket."
5. "Weak." It might mean bad or lame. That's the OLD slang definition. But there's also another definition. If something's really funny, you might hear someone say they're "weak" from laughing so hard.
( USA Today )