The time that I kissed my BIL. My ex-husband's family is very touchy-feely, they all hug and kiss on the lips and I always thought it was very weird because I was raised to be more formal. This kiss happened early in my marriage and I wasn't yet used to having his family put their hands on me. In my mind, only husbands and wives touch and kiss. So when my BIL, who looks very much like my ex-husband, same size, same shape, same hair, etc. came up behind me while I was doing dishes at their grandma's house after Christmas dinner and put his hands on my waist I turned and planted a kiss on him that wasn't very sisterly! Didn't notice until I had my tongue in his mouth and he wasn't reciprocating. I think it's funny now but it was years before I could look him in the eye after that!