A
Afterburner - As in, "shove it up your afterburner."
Alpha Trion - His name gets taken in vain on occasion in the cartoon.
Apprentice - Amoung artists, considered rather degrading, if the subject isn't actually an apprentice.
B
Bit-Brain - Used where a human might say "pea-brain."
Blast - General explicative. Canon, and common in comic books in general.
Bootleg - Approximatly equivalent to "bastard".
Bot Fragger - One would think that since "fragging" generally involves killing or badly damaging someone, that this would be a compliment among Decepticons.
Bot fraggin son of a Cessna - Insult used among Seekers.
Burnout - Term for a robot past his prime.
By the Celestial Spires - General exclamation. Canon.
C
Cybertron Below Me - Roughly equivalent to "my God" or "What on Earth?" depending on context.
D
Dim-spark - Meaning is similar to "dim-wit".
Dirtkisser - Derogatory slang among flyers for those who cannot fly.
Dustkicker - Derogatory slang among flyers for those who cannot fly.
F
Filthy Retro-rats - General insult. It has been suggested that retro-rats are nasty, parasitic things.
Frag Me Flying - Explicative used among Seekers.
Freen - Also, "Freening." General swear.
Frell - General swear.
G
Gasket Breath - Rumble uses this one in the G1 cartoon. A gasket is a seal placed around a joint to prevent the escape of air, so the insult appears somewhat self-contradictory, not to mention the fact that it begs the question, "You mean they do breath after all?" Maybe it's just a general insult.
Get Recycled - Use... your imagination.
Glitch - Most likely a Transformer equivalent to "bitch".
Go Jump In A Smelter - General insult.
Great Xal - General oath. The G2 Cybertronians seem to see Xal as god or saint or something.
Groundpounder - Derogatory slang among flyers for those who cannot fly.
H
Half-clock - Can be used as an adjective ("What are you, half-clocked?") or a noun, ("Shut up, half-clock") to indicate that someone is stupid or slow.
Holy Heterodyne - Seems to be pronounced "Hetrodyne" in the show, but the Webmaid thinks this is what they mean. From the G1 cartoon. This one just cracks the Webmaid up, bad. She's not going to go into the exact details of what heterodyning is, but it seems to be used as an equivalent to "Holy cow!".
I
I Don't Give A Flying Frag - Used where a human might say, "I don't give a darn."
Interface - As in, "He don't give a flyin' interface." Roughly equivalent to an Anglo-Saxon curse word referring to the act of procreation.
K
Kite - Effective, if mild, insult against jets with big wings.
Knock-off - Approximate equivalent to "bastard".
L
Leaking - Used where a human might say "bloody."
Leaking Lubricant - Ironhide uses this one quite a bit in the cartoon. An expression of exasperation.
Lugnuts - General exclamation of exasperation ("Oh, lugnuts!").
Lump - Useless, stupid, and ugly besides.
M
Manifold Mouth - Manifold has a lot of different meanings, from many/varied to a pipe or chamber with multiple apertures for connections... could be a way of saying someone talks too much, perhaps.
Matrix - Obviously not a swear by itself, but it can be used in swears, such as "Matrix blast you!"
Microchip Moron - Stupid.
Miss-clock - See half-clock, but it also hints at a bit of insanity, too... they're more than just slow, their internal timing is off kilter enough that their processors aren't even working in a normal mode.
Mother Fragger - Robots have mothers?
Mudslogger - Derogatory slang among flyers for those who cannot fly.
O
Ornament - Loosely translates to "useless person" with shadings of "arm candy."
P
Piston Head - General insult.
Poprivets - General swear.
Prentice - Amoung artists, considered rather degrading, if the subject isn't actually an apprentice.
Primus - Originally from the comics, I hear it's also used in Beast Wars. Debate as to whether it should be allowed in strict G1 cartoon based continuities is ongoing. Transformer God basically.
R
Repaint - An insult amoung the artistic community.
Rusty - General insult on one's health and cleanliness.
S
Scrap - it pretty much means crap.
Shock - General swear.
Sine Function - As in "Leadership my sine function." (Starscream in Roll For It). The Webmaid's mathematical-technogeek side keeps wanting to analyze this one... is it a reference to his clocking circuits, or what? But Starscream uses it where a human might say something like "Leadership my left big toe" (or perhaps something along those lines, but cruder).
Slab - Useless, stupid, and ugly besides.
Slag - Used all over the place, probably from the comic. It's the mass left as residue when smelting metallic ore, so it could probably be paralleled to the 's' word.
Slag For Brains - Used where a human might say, "Poop for brains."
Slaghead - Used where a human might say, "Poophead." Or something.
Slag-sucking ____ - General insult, the blank can be filled with a number of things.
Slot - Used all over the place. Probably originated in canon. Not sure about any exact definition in this reference (since the word 'slot' can mean a lot of things in English), it appears to be a general exclamation of annoyance/irritation/anger, much like the way certain 's' or 'f' words are used in English-speaking countries. Perhaps, if certain kind of "plug and play" behaviors are used, it is the Transformer equivalent of a certain 'f' word.
Son of a scrapheap - Used where a human might say "Son of a gun." (So, would a robot built by Megatron be considered a Son of a gun?)
Spawn of Unicron - Used where a human would say "bastard".
T
Terran-taint - Used as a noun. It's a derogatory way to refer to anyone who either has an Earth alt-mode, or has spent enough time on Earth or exposing themselves to Earth culture that they've begun to absorb some of it. Just showing awareness of human culture is enough to get you that label in some characters' books.
Tinfoil Turkey - General insult.
Tricurse - As in "Tricurse you," or "Tricursed ."
Trinket - Loosely translates to "useless person."
W
Waste Outlet - Do I have to define this one?
Web-breath - An insult for spider-Transformers.
Well, I'll be reprogrammed with a rivet-roller - This one's obviously from Ironhide, and the Webmaid is not even going to try to go into any literal meaning or technical derivation.
What's your malfunction?! - "What's wrong with you?!"
Why don't you go reformat yourself with a lug wrench - General, if long, insult.
Wingnut - General insult.