If we're talking about the last person I kissed in a romantic manner, then that person does not exist. If we're talking about the last person I kissed who is not related to me and of the opposite sex, then that would be Matt Merritt when we acted together our senior year of high school in the play The Universal Language. If we're talking about the last person I kissed, period, then it would be the 6 year old girl Carly that I said goodbye to for the day by giving each other hugs and kissing her on the cheek.
On a side note: kissing is weird and I don't get it. Granted, my experience is clearly quite limited. Sometimes I watch a movie and think to myself "if that's what kissing is like, then sign me up" and other times I think "Oh man, please make it stop! That woman is drowning, save her from the man with the mammoth lips."