something that is so completely ridiculous on its face, that one must assume that the person who suggests or insists on it must be cognitively deficient to an incredible degree.
unpaid internships are retardulous. adjunct professorships are retardulous.
Wrapped up on something so bad that you act retard to the ridiculous state that makes everyone think you are horrible.To be retarculousable, you have to be exactly llike him/her.
Someone (or something) that overtly appears to be retarded, however, upon closer inspection, appears to be awesome. May be applied to something so stupid that it is cool.
"That girlover there is an idiot, but I heard she is easy...she's so retardicious."
"That girl at the other table is a total pig, but shes hot... pretty retardicious."