A portmanteau of the English swear “shit” and “Squidward”, the name of a character on SpongeBob SquarePants. Typically interjected in situations of surprise or shock, however can also be used as an insult.
A male who impersonates females online - particularly on sites that are primarily geared towards a male audience (sports, sci-fi, automotive, etc.) - in a desperate attempt to become more popular and fill the empty void his life has become. The retardness comes into play as he continually gets caught since he is far too much of a simpleton to pull it off.
The pathetic shimtard just gave himself away again. He randomly said his bra size was 34 Triple C. (A real female would know that the sizes go A, B, C, D, DD, DDD, etc. There's no CCC.)