Despite what you see in the movies, military engagement is a lot of standing around and waiting for orders. So a platoon of Swedish Marines stationed in Afghanistan decided to relieve the tedium with a balls-out lipsync to "Greased Lightning" from Grease. 

Military men and Broadway showtunes—Where do we enlist?

For what it's worth, Sweden has allowed gays to serve in the military for ages. (Check out the upper left corner of the clip at the 1:00 mark.)