Once. In a hotel. I went to the shower and walked straight into the plastic/plexiglass/whatever shower doors without even stopping. I think I was without contact lenses then. My reactions were the following - "wtf was that" - "damn that's LOUD" - "all hotel must have heard it" - "that is absolutely hilarious". Didn't break neither myself nor the shower.
I still laugh at myself every time I remember this.
even when I'm typing this. 
I still laugh at myself every time I remember this.
even when I'm typing this. 
This was in the 1970's when most folk had single glazing, making it easier to break than double glazing. At my parents house in those days they had frosted glass doors. On hearing of someone falling into one and dying from their injuries my dad a coachbuilder/joiner replaced all the glass doors with fully wooden ones.