I definitely one-strapped it, starting in 7th grade... was amazed to read that this is no longer the cool thing to do!

http://www.slate.com/articles/life/cool_story/2013/10/two_straps_on_a_backpack_or_one_strap_what_s_cool.single.html

Did you one-strap or two-strap your backpack in high school?