Here is a story I tell in my book. But in greater detail:
When I lived in Coventry as a student in 2004 I once got high and went for a walk.
On that walk I noticed several dirty old men walking about masturbating under their coats. Not all together though - all at different times.
I went to the railway station to buy a bar of chocolate from the vending machine there. And there I saw it - a man obviously masturbating under his raincoat. He was just stood there, masturbating in the central hall of the station!
And nobody else seemed to notice!
I never saw a person masturbating in public before this.
And I haven't seen one since.
I think the drugs boosted my powers of perception.