Transparent Closet/Playing With

Basic Trope: A gay character insists that he's straight despite all evidence pointing to the contrary.

Straight: Bob very obviously prefers the company of men, but when pressed about his sexuality, he insists he's straight.
Exaggerated: Bob has posters of shirtless men in his apartment, a secret stash of Men's Health magazines that are...rather sticky, and has been in bed with several guys. However, he still insists that he only likes women.
Justified: Bob grew up believing that being homosexual is tantamount to being a murderer or a child molester, so he has to keep his gay side under wraps.
Inverted: Bob thinks he may be gay despite banging a different girl every night and reading Playboy as religiously as most people read the Bible.
Subverted: It seems that Bob is really straight after all. He's just a very effeminate man.
Double Subverted: Bob is bi.
Parodied: Bob shops at gay stores, partakes in gay activities, et cetera...but at every one of these activities, he's still insisting that he's straight.
- Bob is still vehemently insisting that he's 100% straight while in the middle of having sex with Roy, his boyfriend.
Deconstructed: Bob never comes to term with his homosexuality and ends up with an endless parade of beards for wives. As he looks back on his life, he realizes he never came to terms with his true sexuality and dies alone and wondering, "What if?"
Reconstructed: Bob eventually works up the courage to come out to avoid the "Deconstruction" prediction from coming true.
Zig Zagged: Bob is either bisexual, bicurious, or questioning his sexuality.
Averted: Bob is upfront about his sexuality.
- Bob isn't sexually attracted to either gender.
Enforced: "Alright, so the gay rights people are on our asses about not having enough gay characters, but the right-wingers are bitching about family-friendly viewing! Wait, I came up with a compromise..."
Lampshaded: "I'm not gay! What, just because I like hanging out with guys makes me gay?"
Invoked: "You know, if you want to come out of the closet, no one will judge you..."
Defied: When Bob starts to wonder if he's gay, he genuinely looks at it from all angles.
Discussed: "When will Bob come out of the closet? I mean, everyone can see it!"
Conversed: "Oh, goodness, another gay guy who insists he's anything but. When will these TV types learn?"
Played for Laughs: Bob is an exaggerated Camp Gay who claims to be straight or asexual.
Played for Drama: See "Denconstructed"

Wait... are you calling me gay? I'm not gay! Just because I enjoy a nice shirtless man every now and then doesn't make me gay! ...I'm going back to Transparent Closet.