the set of questions:
{is, are, am} {he, she, it, they, you, i} {gay straight}?
are of course
rhetorical. the real question being asked is:
this person or group of people appear to be breaching the ground rules implicit in the facts of life as i learned as a pre-pubescent/pubescent. could you update my mental model?
the correct response is almost always:
so long as you butcher something as beautiful and varied as human sexuality into a binary dichotomy you're never going to understand this person or group of people.
or some rewording of the same.
more specifically the question ``am I gay?'' should be replaced by questions such as ``am I attracted to person X?'' ``am I attracted to person Y?'' or even more specifically ``am I attracted to person X when they do A?'' ``am I attracted to person X when they do B?'' ``am I attracted to person Y when they do A?'' and ``am I attracted to person Y when they do B?'' asking specific questions about attraction to specific people help avoid stereotypes. if you feel the need to put yourself in a pigeonhole, classify yourself based on known feelings for known people rather than an emotional prejudice against certain terminology.
the answers to the questions ``is that person gay?'' and ``is that person straight?'' can only matter if the questioner is attracted to that person, and should be replaced with ``is that person interested in me?'' and this can be discovered the same way people have been doing these things for years, flirting.
understand that someone attracted to tall thin smoking men in their early twenties and buxom non-smoking dancers in their late thirties may not be attracted to non-smoking male dancers in their late thirties, regardless of their weight.
there's more to gender than sex and more to sex than dangly bits, more to attraction that whether someone's wearing trousers or a dress and much more to people than meets the eye (yes, even if you're flexible).