Now, this are my meanings/origins for these words, some based in the real world, some based in my head, if you're offended check out Ricky Gervais' blog and you'll see what real offensive posts look like. Without further ado...
"It's/that's gold" Meaning it's great/wonderful/fantasmic.
Originated in the 1849 gold rush. Modern use is to describe comedic jokes or comedic acts. When a comedian tells a good joke and no one laughs, they have the legal right to say: "Come on, that joke is gold!" or "That's gold, people! Why do I waste telling my jokes to lame nobody's who can't laugh worth a snot when I'm dolling out the best jokes in the biz?!?!" Or a variation of those phrases.
This term began as a reference to class. When the class system began in the U.S. classes were put into levels from poorest to wealthiest and denoted by an alphabetical system. The richest class was Class Z. Class Z lacked tact and sophistication as they threw their money in peoples' faces (sometimes literally). Consider Scrooge:
As a general rule, Class Y had similar amounts of money to Class Z, they just didn't show it off as much, and were kinder to those who were of a lower class. As time wore on, people forgot about the alphabetical class system; seeing Class Y in print soon became "classy" in normal conversation. As more time wore on, and the class system became a 3ish part system, classy no longer referred to the rich as much as it referred to the sophistication shown by those of Class Y.
"Lyeberrie" Circa 1880.
Around the same time as the U.S. established public libraries, the ever elusive lyberrie appeared. Some believe this to be a very sour fruit similar to when one gets a taste of their own medicine and finds it to be very bitter. It may also be a gigantic berry which houses books (which would explain requests for lyberrie cards) but this magical place is more evasive than the Loch Ness monster and possibly cannot be seen by the human eye. This term is also considered to be used by people who either: a.) cannot articulate OR b.) actually think a Library is a lyberrie.
"Too Legit to Quit" also printed as "2 Legit 2 Quit" Circa 1991.
When someone tells you to stop you don't stop. Your desires/work/whatever you're doing is legitimate enough to continue on in the face of any challenge. Has been known to be used to prevent suicide: "Dude, you are too legit to quit life!" Should not be used to condone smoking/drinking/drugging/gambling/any other addiction/harmful behavior.
"Jelly" Popular term in France during the years prior to the French revolution (1789-1799). The upper class citizens where know to say to the lower class citizens "Jelly?" in passing as a way of asking if they were jealous of their money and of the fact that they actually had food to eat. During the revolution, the lower class citizens asked the same of the upper class citizens as they were sent to the Guillotine as a way of asking if they were jealous that the poor got to keep their heads and the rich didn't. Contemporary use: primarily in reference to a fruit-made paste for toast, sandwiches, cookies, pancakes and biscuits. Although, in some circles it still can be used in questions about jealousy and in statements of jealousy: "Did you see her shoes? I'm so jelly." (Insert sad face).
"To Catch A Predator"
This phrase has been around since the beginning of time. As long as there have been predators, there has been the mentality/hope to "catch a predator". This phrase means either to literally catch one in a net/cage/other device or on film (It is well known that prehistoric man where the first to invent the Polaroid so they could take photos of predators (along with family and sometimes attacking family) and they couldn't wait 24 hours to get it developed down at the closest convenience store, so they invented the Polaroid camera.).
On a quick side note, for years I've been telling people about the threat of Raptors (especially during the rapture) and not the basketball team, those guys are pansies when compared to the (Veloci)raptor of the Jurassic period. Now, I can't quote the wonderful lines beautifully acted by the great Sam Neill in Jurassic Park due to copyright reasons, (more so because I wouldn't do them justice) but I think after seeing that film (and the millions of nightmares later) that we can all agree that a raptor is one freaky predator, much worse than the predators of today. In this day and age we see a lot of predators from wild animals to 60 yr old creeps pretending to be 14 in online chat rooms. And while we are more aware of our online predators, let us not forget those of the past, or you may be surprised who shows up at your house to meet your 14 yr old daughter. Naked and with a 6 pack...