In the early 1980s I was flying from Dubai to Bahrain on a Gulf Air B737. We boarded the aircraft via steps to the rear door. Because of the way the door opened outward, we had a great view of the inside of the door while climbing the steps and it was a bit surprising to see a couple of huge arrows "painted" on the door in bright green chinagraph marker. The arrows pointed at the top and bottom left corners of the door and I couldn't help wondering if this had been done to help the crew when closing.
Sure enough, when closing the door, 2 crew pulled and pushed in the corners to get the door closed. I spent the time to Bahrain wondering if this all meant the door was twisted or the airframe!
The funniest door incident I saw was on an RAF Argosy in 1967. On our route from Aden to Francistown, we had stopped at RAF Eastleigh. Prior to take off, someone came down the ladder from the front office and tried to get the rear left door closed. Having had one go, he returned back up his ladder, then reappeared for another go at the door. Back to the flight deck and once more back down to the door for at least three visits to the door.
We were guessing that there may have been in indication on the flight deck that the door was not closing properly. After the 3rd attempt, this bloke must have thought "sod it" and off we went. After a few minutes climbing out, the door made a loud whooshing sound, swung inwards for about a foot, then slammed itself shut. Job jobbed!
There were more than a few wide eyes and raised eyebrows from the half a dozen passengers who actually had seats, a collection of brass, including an Air Vice Marshall. They were sat a lot closer to the offending door than us oiks perched on poles along the length of the fuselage.