I never expected my coworker to see *that*...
OK, help settle a ridiculously overanalyzed debate at work.
Assume you wish to enter a restroom you know to be a single-person restroom not restricted to any particular gender. The door is closed and you can't easily ascertain whether the light's on, and therefore whether someone's in it, or whether the door was just accidentally closed. Assuming the following additional information, do do you test the handle to see if it's locked (and open the door if it's not), or do you knock first (and then test the handle if you don't hear an answer)?
[Poll #1511654]
Assume you wish to enter a restroom you know to be a single-person restroom not restricted to any particular gender. The door is closed and you can't easily ascertain whether the light's on, and therefore whether someone's in it, or whether the door was just accidentally closed. Assuming the following additional information, do do you test the handle to see if it's locked (and open the door if it's not), or do you knock first (and then test the handle if you don't hear an answer)?
[Poll #1511654]

no subject
2) Count to three while awaiting a response.
3) Try door.
4A) Apologize profusely when someone screams in surprise.
4B) Use the facilities after closing and locking the door.
Addendum to 4B) In the event the door is not lockable, whistle while you work.