Leggings made out of material used to make sweat pants. Therefore Leggings combined with sweats equals sweggings. Similar to jeggings which is leggings made out of denim or looking like denim.

When you eat dirt for the first time and leave your family to build a shack in the woods

When you see a super cute sweatshirt and super cute leggings, but you want them together as one. So you go to the front desk and say I want blah blah blah sweatshirt and blah blah blah leggings as one, they hand you a swegging!