I automatically corrected it in my mind, and put quotes around it so that he just made a side remark "Beat." meaning he was tired. i.e. "Beat." meaning "I am beat."
My own problems generally come about when I make a change, and don't totally erase the old sentence while adding the new one.
Or I mean to change the sentence, but neglect to remove one of the old words that is now meaningless or (usually) redundant.
I hate it when I do that.
That is when it is good to have a sharp eyed competent editor nearby.