A phrase used when one is being weird, or awkward. Especially used when there is nothing else to say, or someone has said something uncomfortable.
Or good at science..
Aileen: Sloanzy, I think you are beautiful.
Sloanzy: .. (awkward silence)...
Sloanzy: Sick freak.. (walk away)
Billy: Yo, CHeck out DiS siCk FreaK
Someone, who does something disgusting, or tragic
Brooke: I gave sam a blowie last night
Mo: you SICK FREAKK!!!!!!!
A sick freak is a person or person(s) who wants to see doo doo streaks in your underwear...ehem...HANKE!...PHIL!
"All you sick freaks in the club tonight....pull off your skippies and throw up your stains!"