what is a lock in party?

Question

for adults

Answer 1

You're locked in, until pick up time.
At pizza places, usually 12 midnight to 6 or 7 a.m.
No one out -and only parent can pick them up.

Only way to get out is to get kicked out for misbehaving or violating the rules. (They'll call the police)

Answer 2

They used to be a party someone had.........and you couldn't leave til the next morning unless your parents gave permission