a jacket you wear to frats because you don't mind if at the end of the night, it is covered in beer, frat sludge, or other unidentifiable liquids. Also, it is not a big deal if this jacket is lost during or stolen during the course of the night.
Person 1: Ah, I made the mistake of bringing my J.Crew pea coat out last night and now its covered in beer!
Person 2: You should have brought your fracket instead!
A worn out/disposable jacket usually worn to fraternity parties, because of the high probability that it will get dirty, beer soaked, lost, or torn. Sometimes can even refer to a sweatshirt worn over your normal clothing to said events.
"I lost my coat last night at that party....good thing it was just a fracket."