One insult that starts with the letter 'c' is 'carrot top'. Many people that have red hair do not like to be called a carrot top.
Ard Tard
knave
· homely
Ugly, unattractive...
stupid suckish
Are you serious? Seriously? Oh No...
Obese, ogre, oafish, etc.
dumb. example:hey! kid your a dumb boy/girl. there you have it
Dork. Dummy. Dimwit. Doofus.
intervene, improvise,insinuate,insult,interagate
investigate interview initiate inoculate insult isolate insist insult inflate isolate invite inhale insert intrude instruct instigate incinerate