WTF in a bar

Me and some friends went out to a bowling alley/bar tonight. One of my friends smokes, which is totally fine and nobody cared. She had smoked one cigarette and had put it out in the empty ashtray. A little later, when someone comes to pick up our empty glasses, she puts a COMPLETELY FULL ashtray on our table, and takes the practically empty one with her. She then walked away.
WTF? We were just staring after her for a while, but she didn't come back, so we just grabbed an empty one from a table and put the totally disgusting stinking one on an empty table. It was definately weird.