something that makes you feel sick to your stomach, nauseous, or just wants to make you throw up. However, the sickness that you feel is usually not physical sickness, but rather a type of psychological sickness. Can also be used to describe any regular son of a bitch or a disgrace to society. A variation of the word in the adjective form is "sickening"
Ugly kid: "I'm handsome"
You: "No, that's a sick joke"
1b. A kid walks by you wearing crocs; consequently you tell them, "you're a fuckin sick joke."
1c. John:"That ugly kid actually get pussy"
You: "And the sick thing is he probably has a small dick too"