Top definition
A sixpack that has slowly disappeared due to less exercise caused by adulthood responsibilities.

High school athletes are highly susceptible to this once they enter their undergraduate year of college, trying to find time to study and workout. Ultimately, the student who chooses to study over working out develops a flatpack.
Dude I used to have a killer sixpack, but I'm stuck with a flatpack now that I have to adult.
by Lercules November 02, 2017
Get the mug
Get a Flatpack mug for your daughter Riley.
A small Chinese,Vietnamese or generally asian kid that is brave and loves rugby.Has potential as a back or flanker and either uses steps or is very fast.Normally dirty minded but is a good friend that will back anyone.Very talented at all sorts including sex,music,art and sports.
by hackerpro June 13, 2012
Get the mug
Get a Flatpack mug for your boyfriend Manafort.
A pack of cigarettes that have been flattened by a person who has carried them around all day in a back pocket, also known as a flatpacker.
Man, i was gonna smoke a cigarette but i got a flatpack!
by Angie Says So June 08, 2015
Get the mug
Get a Flatpack mug for your Facebook friend Bob.