wtf...you sound like someone fresh off the boat trying to learn english slang. the correct insult is "r****d" but even that term is a bit derogatory because down's syndrome is a serious condition. try "fool" or "idiot" or "dumba$$" or "true beaner" all of those terms equate someone with a very low IQ despite the fact that they are not mentally handicapped in any way. in short: what Deckard said.
