rectal creature

Is someone who is socially awkward, Weirdo.
This phrase is originated in Hebrew - Yetzur Me hatahat
Yetzur - Creature
Me - From

hatahat - The ass

Can be used in a simpler way :
Creature from the ass

Rectal creature is using medical reference for more

sophisticated insult.

"Look at this weird looking dude! he's such a rectal creature!"