![1boy 1girl abs arms_around_neck bed_sheet blurry blush bouncing_breasts breasts brown_hair carnelian censored cleavage closed_eyes dutch_angle floating_hair from_above game_cg girl_on_top head_tilt hetero hikami_michie hug indoors large_breasts leaning_back moaning mosaic_censoring motion_blur navel nipples open_mouth penis puffy_nipples pussy raised_eyebrows red_hair revolver_(game) sex short_hair sitting solo_focus sparkle straddling sweat upright_straddle vaginal rating:e score:5 post #109742](/cdn_image/preview/ec/35/ec35c6a3759cd2ce630ab2882a5f4f5c.jpg)
Refers to breasts in motion, often as part of a .gif or flash animation. If it is not an animation, something like a motion blur or movement lines must be present to convey a sense of movement.
If one breast is up and the other is down, add the unaligned breasts tag as well.
Example: post #694780.
This tag implicates breasts (learn more).