This is a from a few years back, and I cannot remember where I was flying to/from, but...

The plane door closed. I was in the exit row, door side aisle, and a Dutch man who was also a PM was other side aisle seat. The flight was quite empty. The flight attendant started the safety message but stopped. The plane door opened. Two women got on the plane.

The women appeared to be friends. One of the women (both mid-thirties, looked a little weathered) immediately went to the back of the plane, returned to her seat a short time later. The flight attendant started the safety message again. Once again, the plane door opened. One of the two women - the one who had not walked to the back of the plane - was escorted off the plane.

The door closed again, and the safety message started again. I think this was the time the FA actually completed the message. Once again, the door opened. This time, the woman who had been taken off the flight was back on with a GA. The woman escorted off claimed to have had a carry-on. It could not be located. The GA and FA decided this woman was fibbing. She was escorted off again and, once again, we heard the safety message.

The other woman then explained to the Dutch man and I that she had met this woman in the airport bar and the other woman claimed she stole her bag. She had gone back and reported this to the FA.

When we landed, the woman still on the plane went backwards on the plane, took a bag out of an overhead, and started walking off the plane with three bags. Out of nowhere, the Dutch guys screams, in Dutch, but then in English, something along the lines of, "That woman is a thief." Sure enough, the FA looks over and says, "Ma'am, I'll need to see that blue bag."

Although I didn't stick around to be sure, it seems the woman thrown off the plane was the one telling the truth, and the woman still on the plane had stolen the bag.