![1boy 1girl absurdres arm_up bed black_hair bouncing_breasts bow breasts breasts_apart collarbone eyebrows_visible_through_hair frilled_bow frills hair_bow hair_tubes hakurei_reimu heart hetero highres large_breasts long_hair lying missionary navel nipples nude on_back on_bed open_mouth penis pussy pussy_juice red_eyes saliva sex shefu shiny shiny_hair shiny_skin speed_lines spread_legs touhou trembling uncensored vaginal rating:e score:8 1boy 1girl absurdres arm_up bed black_hair bouncing_breasts bow breasts breasts_apart collarbone eyebrows_visible_through_hair frilled_bow frills hair_bow hair_tubes hakurei_reimu heart hetero highres large_breasts long_hair lying missionary navel nipples nude on_back on_bed open_mouth penis pussy pussy_juice red_eyes saliva sex shefu shiny shiny_hair shiny_skin speed_lines spread_legs touhou trembling uncensored vaginal](/cdn_image/preview/e8/74/e8744e5a7756171e6077e9d5186a2c48.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).