Back in the 1980s and 1990s, High School athletes would give their girlfriends their letter jackets to indicate that they were property of the bro.

[This bro doesn't have a GF, but if he did, he would give her his letterman jacket, spike her bangs, and carry her hammer for her in his painter's jeans hammer-loop.]
These days, altbros & altMen give their GFs an oversized shirt/jacket/hoodie in order to indicate their possession of the soul/body of their moderately alternative woman.

This trend is less about fashion & more about possession.
This trend is less about who u r & more about who some1 else tells u 2 be.
This trend is about giving up control of ur self concept & letting some1 else make decisions for you.
This trend is about accepting the natural fact that some women just can't make it on their own, and they need a man to construct values & rewards systems for her.
This grl has a very electro boyfriend. The bigger & brighter the shirt is, the more he loves her/is controlling & possessive.

What does an electro candy cane taste like, yall?
[Photos by Hel Looks and Dam Style ]
More girls wearing their BF's shirts after a slumber party/tugfest.
http://www.hipsterrunoff.com/2008/07/another-girl-who-slept-over-at-her-bfs.html
http://www.hipsterrunoff.com/2008/07/i-slept-over-at-my-bfs-last-nite-yall.html [She's kute.]