I felt bad because on my ride from SF to Berkeley I took up two seat as it was the only way I could fit my bike without having it take up standing room... So this girl, Daphne, started sort of leaning on it, and eventually was propped up on it.
At one point I looked at her and smiled and she asked if it was my bike and if it was cool for her to post on it. I said it was fine and before I knew it she was fully perched.
She was quite lovely and we had a great chat.