The landlord put the doorknob on wrong because he was too lazy/stingy to buy a new one after the key was lost by a previous tenant. The button that locked it was on the outside. I had gotten into the habit of locking doors after me as I lived alone in the apartment. I locked it after me after I went inside but had forgotten that the key was on the table outside.
The main door didn't have doorknobs; just the keyhole. I don't quite know how I messed that one up but I left the keys stuck in the hole outside and I got locked in.
Both these happened after my daily 14-16 hour workdays.
Has anyone ever had to use the credit card trick on a bathroom door? Done it about three times already. The kids like to lock both bathroom doors.