What do you think if I constantly ask my friend if his dad is gay.
Why would you question him about his father's sexuality?
I don't trust straight guys. They always lie about it.
I don't think it's very kind to try to pry into the sexuality of others if they're not comfortable. These questions can be really sensitive. How about just asking their opinions of sexuality so you can try to learn more about it?
How would you feel if I asked you about your sister's breasts?
I would feel a little upset and wonder why you are asking that.