Here's a question which I am going to apologize for in advance:

Have you had instances of where PAXs would not come out of the lavatory on board an aircraft in what appeared to be a reasonable time to do *ahem* almost anything, creating both unwarranted concern and inconvenience for other PAXs?

The reason I am raising this question is that a few weeks ago I was about 8 1/2 hours into the JFK NRT flight, just prior to crossing the International Date Line, and I noticed that a line of about 4 PAXs had formed outside one of the bathrooms.

Nothing unusual, but about 20 minutes later the same PAXs were still waiting. The other 3 PAXs gave up and went to, I presume, other facilities. I joined the now 1 person PAX line. Two minutes later still no indication of if or when the PAX inside would be coming out. The PAX in front me finally left in a huff. I knocked on the door. No answer. I then opened the door ever so slowly and carefully not knowing what to expect...empty!
As it turns out, the vacant door sign was malfunctioning and indicating that it was occupied when it was not.

Other than just plain common sense, what is a reasonably waiting time before a FA should be alerted? No one bothered after almost 30 minutes. Japanese politeness??? As it turns out for good reason !

Have you ever caught anyone smoking in the lavatory? How did you know? Did the smoke alarm go off? Can you open the door from the outside to the lavatory just in case the PAX refuses to come out? Are PAXs ever fined, arrested for lavatory misbehavior?