The only correct way to wear the mask for anyone is with the blue side facing out, according to an instructional video from the World Health Organization.
Each layer of a surgical mask serves a different purpose that is most effective when worn with the colored side out and white side in. The inner white layer is absorbent and meant to capture particles when the wearer speaks or coughs. The outer colored layer is fluid-repellent and meant to keep out viruses and bacteria.
Some social media posts claim incorrectly that healthy wearers should have the white side out to keep germs out while sick wearers should have the blue side out to keep their germs in.