The stage entered when one is eating a burrito and cannot set the burrito down because it would fall apart. This is generally due to lack of structural rigidity because of poor construction.
Larry: Hey, could you grab me a napkin? I’m in burrito lock and can’t get one.
Phil: Sure thing, buddy-guy.
Pierce: What do you think of the new burrito place?
Nick: The food tastes good, but they don’t know how to roll a burrito. The last two times I’ve been in there, I’ve end up with burrito lock.