Marco bodt from the anime Attack on Titan, known for his freckles. When Jean imagines Marco in front of him, a light shines behind Marco. That making Marco freckled jesus.
Basically someone crazy. Kind of a synonym of "freak", but there is no humor in calling someone a freak, so if you want humor, call them a freakasaurus.
Freakasaurus was also mentioned in episode 15, season 2, of Star Trek: Voyager.
Postulated by a non-freckled human. The theory proposes with enough sun exposure a freckled person's freckles will eventually connect - seemingly making them very tan, but in fact just making them a giant freckle. This theory has not yet been proven, only tanning creams have helped self-loathing freckled individuals achieve this.
Steve: Did you see Martha the other day?
John: Yeah she's been on the beach every day; testing out the freckle theory I presume.
Steve: She sure would make one sexy giant freckle!
John: True story.