The cascading flab that cliff-hangs over a belt buckle, or in particular, a pair of tight fitting hipster jeans. Most commonly seen on chubby pubescent girls.
"Will you just check out the fatalanche standing in the McDonald's line"
by Leha March 26, 2005
1 more definition
Alt Def: When the flesh rolls of a morbidly obese individual land on you while sitting at a sporting event, public performance, or on a plane, bus, or train.
Ex. Jack almost got buried in a fatalanche when a giant fat kid sat next to him at the Tiger’s game.
by zookpr April 16, 2009