For me, the issue isn't being offended, it just pisses me off. It doesn't make any sense when there are already so many other words to express displeasure or negativity that one would choose to use a word that is associated with a group of people's sexual orientation. Ultimately, I think that anytime you co-op a phrase or word that would otherwise be positive and use it to harm and/or refer to something in a negative way, it's juvenile and ignorant. I don't see how it's any different than using racial epithets.
And I will call people out for doing it.
And I know I can't speak for the entire LGBT community, as I'm sure there are people who use the words jokingly, but as heterosexual person, it upsets me when I see that kind of thing happening.