Outties are jeans that appear to be inside-out, inspired by the 2015 fashion trend in Back To The Future II. As you may recall if you haven't already destroyed your brain with drugs and alcohol (I sadly could not recall), Doc warms Marty to "Pull out his pants pockets" because "in the future all the kids wear their pants inside out". Remember when Kris Kross made wearing your jeans backwards the cool thing to do? I peed my pants at school so many times because I couldn't get them off in time. Don't have the €99 (~$110) to buy a pair? Just wear a pair of your existing jeans inside-out. Sure you won't be able to access the pockets, belt loops or fly, but you're wearing your pants inside out -- you're a crazy person, you don't need those things anyway.
Keep going for a couple more shots and the Kickstarter video.
Thanks to Marcus O, who always wears his shirt inside-out after lunch because stains.