sidepec
When the outer side of the chest is visible through a gap in the clothing being worn by the subject, or if only the side of the chest is visible like from behind positions.
Example: post #4805923
If the nipples are visible, use nipple slip as well.
Example: post #4343645
Nipples do not disqualify this tag, unlike the sideboob tag.
Do not confuse with pectoral cleavage.