1) When my husband mentions bowel movements. Enough said. Why, husband, why?
2) Being on anything that is fast. This makes poor Mr. Adventure sad, since he owns a motorcycle that I refuse to ride. I decided early in life that I was never going die in a motorcycle accident, and thus will never accompany anyone on such a death contraption.
3) Seeing a steamy sex scene while in the presence of my spouse. When I'm watching a movie by myself, I can fast forward or look away. But when I'm with my husband, it just adds another level of awkwardness. If a movie has more then one such scene, I'll usually turn it off. I want my sex life (and what my head thinks about sex) to only include my husband and nothing else. I desire to keep that part of our life private and sacred! No thank you, other people's sex, you are not needed.
What makes you uncomfortable?