Terry is from the future. They use different slang in the future. So here, for your convenience, is a (partial and under construction) dictionary of future!talk, compiled from the show and occasionally made up by me. Anything non canon will be clearly marked as such.
Arkham: Crazy "Guess I have gone arkham." Note: this term is likely more uncommon than some on this list
Blip: Ignored, denied, blew off, shot down, etc, with 'blip' standing in for the other slang terms. "He blipped you off" (upon being stood up); "the system blipped you" (upon being denied a hack) etc.
Cin[n]th: Non canon. Also known as cyn[n], cyn[n]th, and cin[n], it's a drug of the future noted for triggering a feeling of euphoria and a dreamlike state, and for a taste that resembles cinnamon.
Credits (or Creds): The general currency of the future, which has moved on from paper and metal money to plastic cashcards, with varying limits.
Dreg: A person lacks ambition or status; "lowlife." Possibly a curse word, presumably highly offensive, probably both. People aren't generally called this, particularly to their face.
Fiz: Soda or possibly future!beverage.
Frag: It seems to be a strong general purpose curse. It may mean something along the lines of "death" "dead" "die" or may just be used as a catchall, much as a certain other word beginning with f is these days, which seems more likely. Let me re-emphasize, however, that this is a very uncommon word. Terry has thus far said it once in canon, iirc.
Frosty: Cool, quiet, still, etc. "Stay frosty" when telling someone to stay still and relax, not to move.
Glitch: General slang for problem or difficulty. "Whatever glitch you had with him..."
Glitching: Likely means causing problems, though may mean whining, moaning, complaining, etc.
K: Non canon. (Kind of.) Drug of the future, manufactured (secretly) by Lex Luthor. It is presumably addictive, and triggers feelings of euphoria. The notable, if secret, ingredient is trace amounts of kryptonite, as it was manufactured as a way to get kryptonite into the bloodstreams of junkies and thus cause Superman pain when he gets too close to the people of his city. Usually you won't find k anywhere but Metropolis as a result. The drug itself actually is canon, but a name is never provided, and so the name is not.
Moloko plus: Likely crazy, corrupt, or generally downhill. "Soon as the weather turns, the whole city'll go moloko plus again."
Neurospray: A tranquilizer (and probably controlled substance) that targets the aggression centers of the brain to calm people, and make them docile and easy to handle.
No-tech: A society of people who choose to live without modern technology and spurn the 'tech world'; in many ways their society resembles Amish society.
Rae: Non canon. Also known as Ra, Ray, and Rai. Rave/Recreational drug of the future, it is a hallucinogen/happy drug that makes you feel as though you can do anything, which in turn can lead to being really stupid. "Are you on rae?" is therefore an equivalent phrase to "What are you smoking?" or "Are you high?", used in the same WHAT ARE YOU THINKING context that the latter two are used today.
Rips: Verb generally synonymous with the slang meaning of "rules" or "kicks"
Scammin[g]: Lying, fooling, tricking ("I'm not scamming") Note: This word is likely slightly more uncommon than some on the list.
Schway: Adjective generally synonymous with "cool," "awesome" etc.
Slag: General purpose expletive used both as a noun and verb; milder than 'frag'
Slammin[g]: 'Unbelievable', used both in the more normal sense of the word and as a synonym for cool/awesome etc. ("This is slamming" or "You're slamming me")
Slaphead: A person addicted to slappers
Slappers: Future drug that resembles a nicotine patch gone horribly wrong; paper squares coated with a highly addictive drug called Venom, which seems to function like a cross between heroin and steroids. When applied to the skin, the user's muscles swell and strength goes wildly up as pain sensitivity goes down. There may be some mood-altering aspects that go with this, though it's entirely possible that it's merely circumstantial. It may increase aggressiveness or decrease the ability to think rationally. If the drug is cut off, the user goes through physical withdrawal symptoms similar to heroin -- shaking, pale and clammy skin, extreme exhaustion and lethargy, physical pain -- and, as with heroin, it can burn a person out, until they are dependent on the drug to do anything, and eventually are left as a burned out husk even with it.
Slow-pulse: Verb; calm. "Everybody slow-pulse it!"
Soars: Cool/amazing. "This camouflage option really soars!" Note: This word is likely slightly more uncommon than some on the list.
Spacie: Basically: space hippie. Mostly they want space travel to be free for all so they can head off to Vega.
Spiz: Spazzing, freaking out ("a spiz fit"). Note: This word is likely slightly more uncommon than some on the list.
Splice: Mixing human and animal genetic information in a process that creates a chimera. It can be subtle enough to merely give someone spot or cat eyes, or dramatic enough to change their entire body shape wildly. The more dramatic the transformation, the more animalistic the person becomes, and the harder it becomes to think as a human. It was a popular fashion trend in 2040/41 until studies began to show the tendency of splicing to make someone more violent and aggressive, whereupon it was outlawed.
Splicer: A person who has spliced or splices their DNA.
Spud: Loser, dork; not used nearly as frequently as 'twip'. Can be used as an actual insult or as a term of endearment, much as "loser" etc can be used today. Note: This word is likely slightly more uncommon than some on the list.
Telecom: Cell phones only not. Possibly this applies to phones in general, possibly normal phones no longer exist. Alternate spelling may be 'telecomm'.
Twip: Generally means "loser," "idiot," etc. Likely a linguistic evolution of "twerp" and "twit." It may be used to connotate immaturity. Can be used as an actual insult or as a term of endearment, much as with spud.
Unit[s]: When not being called 'credits', the cash of the future seems to come in units. I guess. Note: This appears to be a wildly unusual term, as it's used all of once, as opposed to lots and lots of people calling their money 'credits' or 'creds'.
Vid: Abbreviation of 'video'. Refers to digital visual media, and is also used to refer to the connected hardware - vid disk, vid screen, etc.
Vidcom: Visual calling device. Think skype, but not limited to your computer anymore - there are scattered public booths much like telephone booths or picture booths where you can make video calls.
web or net?