I once masturbated in a smelly school bathroom
Why did you do that in a school bathroom?
I didn't see the terrible condition of the bathroom when I entered it. YUCK!
I guess it's not totally weird that you did that. However, for sanitary reasons, I would refrain from doing so in the future.
What could happen if someone catches me masturbating?
I guess you aren't doing anything illegal, and the bathroom stalls do give you some privacy. However, it's still kind of strange that you want to masturbate in a public bathroom. I suggest trying to hold it and waiting till you get home to masturbate.