fall in (
http://definr.com/fall in)
v 1: break down, literally or metaphorically; "The wall
collapsed"; "The business collapsed"; "The dam broke";
"The roof collapsed"; "The wall gave in"; "The roof
finally gave under the weight of the ice" [syn:
collapse,
cave in,
give,
give way,
break,
founder]
2: to take one's place in a military formation or line; "Troops
fall in!"
3: become part of; become a member of a group or organization;
"He joined the Communist Party as a young man" [syn:
join,
get together]