I actually had to be reminded that today is National Cleavage Day. National Cleavage Day is not a day created by Hallmark, instead it was created by Wonderbra back in 2002. As Wonderbra brand manager Samantha Paterson describes its purpose:
It is a day for women to realise that their cleavage is something unique and that they should be proud of it.
Naturally it is a day to be celebrated by visual images but after hours and hours in trying to find just one or two tasteful images I realized it was an impossible task and realizing the gravity of the situation I decided to leap into the breach and randomly pick
So Google always have a cartoon images on holidays and other days of significance why not today? Or maybe the two O's in Google have a special meaning today.
On the historical side; The specific word "cleavage" is a derivation of the word "cleave".
Cleave "split" comes ultimately from Old English cliofan/cleofan. There were cognates in Old Scandinavian, Old High German, and Old Norse. The Old Teutonic root was *kleub-, and we even get a pre-Teutonic root with this one: *gleubh! Both meant "split".
The pre-Teutonic root is thought to be the source of Greek gluph- "cut with a knife" and Latin glub- "peel, flay". The Old English inflected forms became cleave, clove and cloven, though cleft appeared in the 14th century and has survived.
Cleavage originally was a technical term in geology (1816). The sense of "cleft between a woman's breasts in low-cut clothing" is first recorded in 1946, when it was defined in a "Time" magazine article as the "Johnston Office trade term for the shadowed depression dividing an actress' bosom into two distinct sections."