Ah, nosebleeds, the hallmark of some lewd pervyness.
Or maybe they got hit in the face.
30 minutes to draw, 15 to submit!
Sources:
https://derpibooru.org/1170822
https://derpibooru.org/1398350
https://www.deviantart.com/siemensohm/art/RainbowDash-x-PinkiePie-Ver-EQG-433150228
https://www.deviantart.com/below-depth/art/Sunlight-2-670516028