Got caught short meself once in Liverpool.
Went into a McDonalds and headed straight for the jax.
I could here 'Excuse me, excuse me" from the security guard but I kept walking and didnt turn around.
Came out later and there's your man blocking the doorway commenting that our toilets are for customers waffle.
I pulled open the door and said 'I wont do it again', smiled and walked away. He went ballistic.