Answer:
I did not shake hands with a HIV-positive person
Step-by-step explanation:
When I was a high school student, I met a man that I knew had AIDS. I was unfriendly towards him and I did not take his offered hand in greeting. I discriminated this person by totally avoiding him and not getting involved with him at all, even though he was a friend of my parent's.
I behaved this way because I lacked knowledge about this disease. I thought that it spread through skin contact and that all infected people were from criminal or gay background.
Years later I did some serious research on AIDS and knew that all my accusations were totally false.