Agatha:I hardly know him! Castle Heterodyne: What's to know? His family is powerful, his spark burns strong, he's already taken with you... Agatha: But— Castle Heterodyne: And you cannot deny that he has a magnificent death ray. Agatha: ... That's... That's hardly a basis for a stable relationship. [Blushes]
In post-hiatus Fans!!, due to a totally broken masquerade and a well-respected polyamorous "triad," the hot-button issues seem to be polygamous and vampire marriage. Gay marriage hasn't been mentioned, although it's been implied gay rights have made impressive leaps over the Time Skip. A point of irony is that both vampires and polygamists seem to enjoy Mormon support.
This installment of Sinfest is possibly the only thing in existence to blur the distinction between astronomy and sex.
Ash: I got it all set up for you. Just slip it in. Emily: All right already. Just give me a second. It's the first time I've done something like this. Ash: That's perfect. Emily: I still don't know what I'm allowed to touch and what I can't. It's so gross and oily. Ash: That's perfect. Now put in another one. Emily: This is making my fingers all slippery. Ash: You get used to it when you do this for a while. Rumisiel:(listens in, drooling)
The awesome topper to this conversation is when Ash's dad arrives, asks Ash to go pick up dinner, and asks Emily, "Do you eat fish?"
In Coming Up Violet a mini-sex scandal develops around the titular character when her boyfriend starts spreading lies about their first date, the boyfriend is on the lacrosse team. Many Americans will most likely remember something similar happening at a certain university in 2006.
The whole "Comic in Crisis" mini-arc from Sluggy Freelance (beginning here) bares more than a few similarities to the Monica Lewinsky scandal that was going on at the time.
K'seliss the lizardman has an embarrassing instinctual reflex happen when he's threatened by mechanical bugs in the current dungeon crawl in Goblins; his head crest raises. Since he'd previously said that he doesn't "swing that way" (he only kills what he can eat, and considers fighting, eating and sex to be subsets of the same category,) he blames his reaction to inedible war machines to be caused by thinking of a "battle he had AGES ago." And he takes time out to see if the other party members have noticed his gallant reflex.
Ozy and Millie turned a Mattress Tag Gag into one of these; Llewellyn (who has declared his property to be a sovereign country) decides to legalize cutting tags off mattresses. The U.S. is not happy with this, and ends up deploying border patrols to prevent people from smuggling mattresses between the two countries. In case you're confused, this arc was written around the time Canada was considering legalizing marijuana. (It failed, but still.)
In Homestuck, the other trolls make fun of Karkat's tiny horn size. Karkat also has an unusual blood colour, which he believes is unnatural and destined to get him persecuted in society, and so 'closets' himself by using grey as his signature colour and getting extremely defensive whenever anyone talks about blood.
Much of the humor from troll-human conversations comes from the trolls not caring about homosexuality or incest, but getting very uncomfortable when someone mentions... buckets.
The author has a habit of putting obvious sexual imagery in the trolls' death scenes.
Vriska impales Tavros on his own lance after he tries to stab her with it. It doesn't help that the two are canonically stalker and victim.
Eridan shoots Feferi and Sollux- his ex-girlfriend, and a boy he was trying to flirt with minutes ago- with his rifle, which is specifically stated several times to shoot "white magic".
The trope experiences a subversion when Clubs Deuce flips the fuck out after realizing the object he was hitting Doze with was apparently a BULL PENIS CANE.
Errant Story has a few of these, one of the better ones coming when Sarine observes Jon fondling her Magic Sword, which has the cool property of expanding from a small crystal to a taut, vibrating focus for magical energy when turned on (so to speak). You couldn't possibly imagine that there might be Unresolved Sexual Tension between those two, could you?
Sarine: Please don't put your finger there.
School Bites: the vampire schoolgirls are given potions to control their bloodlust, so they only have to drink blood once a month.