I was told that "not on purpose" cannot be used in the middle of a sentence. For example:
I was showering and, not on purpose, I participated in the #icebucketchallenge.
I am aware of the fact that there are more elegant expressions such as unwillingly, unwittingly etc etc but my question is: is the above correct? Am I allowed to use "not on purpose" in such a way?
I know there is no language police but there are, seemingly, rules. I posted a sentence in a forum with this expression and I was told it is incorrect to use it this way.