A visible string undergarment worn by someone who's undergarments should never be seen by mortal eyes, resulting in mind-numbing horror and possible sanity loss. Referencing H.P. Lovecraft's cthulhu mythos, where alien Elder Gods lurk around the corners of reality, waiting to feed on human horror and despair. In this instance, that Elder God is a 4-foot wide keester with a silk floss strand splitting the cottage cheese uprights.
Dude, Rosanne's cthong was all hanging out at the bar last night. I think I need to go see a therapist or poke my eyes out with a sharpened pencil.