Common is the trade language of Faerûn. Almost every sentient civilized being speaks a smattering of it and most are fluent. While most cannot read or write the language, generally, the people of Faerûn will be able to converse with each other in this language.
In other realms, "common" may be a different form. An example is the Underdark, as the residents there speak what is known as Undercommon. Inhabitants of different planes might also speak different forms of "common".
The obvious advantage to Common is that practically every sentient in the universe can speak it. Even in remote areas of Faerûn like Murghôm, Samarach, and the Great Glacier, the inhabitants can speak at least enough of it to make themselves understood with a little creative pantomiming. Admittedly regional accents have a tendency to confuse the issue; natives of distant areas may regard each others' accents as strange or silly, but they can still understand each other.
behold the Realms euphemisms for those feminine features politely described as "breasts."
The list hereafter ranges from (listed first) the clinical to the polite through the gently racy and silly to the really raw (listed last), with notes on usage and pronounciation in brackets:
Alpetan (plural form: singular is "alb"), brighthelms, bells, saebur (this is a singular and plural form, as in "Hsst! Catch the saebur yonder!" or "Feast on THOSE saebur, hey?"), fruit, pillows, ramraths (derived from "ramrath," a reddish, round melon grown in the Tashalar), roalen (derived from "rollingheads," from an old and anonymous ballad that compared the bouncing movement of a running woman's breasts to the bouncings of severed warriors' heads being rolled down an embankment by orcs after a battle), puffballs, handheavies, bite-loaves, zarrzem, bitebolds, pluckers.
Of these, a woman speaking to other women might use "bells" when speaking politely of breasts, "pillows" when joking about them, and "bitebolds" when intending to be rude or vicious.
In addition to the listed endearments, ugly, wrinkled, misshapen breasts are sometimes inevitably referred to as "udders."
Nipples are clinically referred to as parlarren (singular: parl) and sometimes called thorns, daggerspikes, or (poetically or more politely, as in one woman to another, or a male noble trying to be daringly gallant when speaking to a female noble) springbuds. When trying to be coarse, speakers usually dub them "teats" or "suckworts."