According to the Associated Press, Cubs closer Hector Rondon got stuck in the bullpen bathroom for a few minutes following the conclusion of Game 1 of the NLDS against the Cardinals, a 4-0 loss.
The lock simply malfunctioned, according to Joe Walsh, the director of stadium operations for the Cardinals.
The Cardinals replaced the lock before Game 2 started on Saturday.
Rondon joins a list of baseball players to get locked in the bathroom which includes Jeff Francoeur (link), Fernando Rodney (link), and Jose Ceda (link).