Def 2: Traditionally used in information security and telecommunications related to a 10Base5 thicker coaxial cable. Also known as THICKNET. It is longer than ThinNet and is more resistant to electrical interference (NOISY ENVIRONMENTS). Non-techno savvy people use the word THICK with the double-entendre above when the telecommunications and information security gurus hack in and think they don't know the victim is aware of it.
Def 2: The telecommunications guy and a rather dodgy neighbor both believe that woman doesn't know they're phreaking her or using the back door to her computer. Gosh, they must be THICK.