We all have good and bad days and it definitely is a bad day when your colleague doesn't respect you.
I had one incident when I was conducting a meeting and my colleague kept cutting me off rudely in the middle and saying his opinion on the matter over me.
He knows that I was speaking and it happened more than thrice, so I told him that I'm not yet done with my speech and continued it without any interruptions from anyone. I don't know if he was trying to be superior over me, but when I shut him down he did not look at me in the eyes.

HAve you had such demeaning disrespecting treatment from your colleagues or co-workers?