What I also find a bit strange is when people feel the need to tell you what their sexual orientation is, even though you didn't ask. What's also strange is when you consider what you would have to ask them to have them give you that as their answer.

And in some cases it could even be considered as sexual harassment.

Example: "I am lesbian" in other words means I'm sexually attracted and may or may not have sexual intercourse with another woman.

Now try to think of questions you would have to ask to receive the above as the answer.

Maybe it's just me, but unless asked, it feels very inappropriate to just tell people with whom you have sex or wish to have sex with. Especially when the topic of conversation was about something completely different and in no way related.