Cable and Deadpool, who star in their own eponymous comic book series, are best friends/partners in crime/enemies/Heterosexual Life-Partners with a healthy dose of Ho Yay. In one issue, Black Mamba uses her powers to distract Deadpool by making him dream of his greatest desire — which is rubbing sunscreen on Cable's back on a sunny beach.
To the evil, evil man's defense, Black Mamba's second mind attack made Deadpool, Cable, Luke Cage, Power Fist and Weasel all fantasize about sunscreen related scenarios, with each other, presumably. There were lots of embarrassment.
And directly after that he drops his pants to prove that the fantasy is bogus and he's "all man" by having sex with the B.A.D. Girls — revealing that he is still wearing the yellow panties he wore with the Marvel Girl costumed he'd donned earlier. You know, when he planned for Cable to be so distracted checking out his legs — and don't think he didn't see Iceman sneaking a peek too — that he wouldn't know what hit him when Deadpool struck? Yeah.
Even other characters comment on the Ho Yay in Cable and Deadpool's sparring matches.
Deadpool: —Good sparring.
Cable: Was missing something...
Deadpool: Massage oil? ... did I say that out loud?
Cable: [Elbows Deadpool in the head] That's what was missing...
Deadpool: Ben-Gay... stat!
Irene: If you boys are quite through eroticizing...?
Then of course are Deadpool's comments about Cable's "naughty bits" and how Cable "could make that techno-organic mesh rise to the occasion when necessary."
When dimension-hopping, he runs into an Alternate Reality!Cable who was taken over by techno-organics and sprouted loads of shiny metal tentacles. When they attacked Wade, he went from "ow! ow! hey—that is incredibly personal space there — ow!!!" to "okay—hey—okay—okay—see, now I'm kinda liking it". Yes, they did just have implied tentacle sex.
Deadpool also seems to seriously consider becoming one with techno-organic alternate reality Cable, because he thinks (or is being influenced to think) that his Cable would want that:
Deadpool: Maybe this is what he wanted... Wanted me to find... Been torn apart so long, in my head, my body, my heart. [...] I can see a unification.
Siryn: This isn't what Nathan would want, Wade. You know that-
Deadpool: But it could be. It should be. He wanted me to find a way to be whole. He wanted me to be whole. I could be whole...
And after techno Cable has been beaten:
Deadpool: Kind of a shame, actually... 'Cause for a second there, it was really kind of nice...
From Cable & Deadpool Issue 10:
The Cat: This is the component you were missing.
Deadpool: But I took everything you had in Japan—
The Cat: Only what I allowed you to take.
Deadpool: You are so totally the coolest...
The Cat: But how do you plan to get it to Cable in time?
Deadpool: We got this whole don't ask, don't tell thing goin'... not that there's anything wrong with that. Bodyslide by two...
The Cat: Don't ask, don't tell—? ...Oh. Oh.
Deadpool's (other) main crush in the series is Bea Arthur. Bea Arthur is about 6'4, white hair, deep voice. Sound like anyone Wade knows?
Starting from the genetic merging incident that led to Cable and Deadpool being read as genetic duplicates, every introduction page that mentions it alludes to this event being on the same intimacy level as sex. Such quotes include:
"Their bodies intermingled in as ridiculously intimate a level as you can have without owing someone a cigarette."
"They fought 'gainst guy tried turning people blue/Made Cable get frozen and Deadpool go goo/Their bodies merged into one conjoined splat/(Not that there's anything wrong with that.)
Unused excerpt from the recorded interviews of Irene Merryweather:
Deadpool: We got infected with this Facade Virus, which made our bodies sort of melt together. It was actually kind of romantic. Now, when we bodyslide, we end up merged.
Deadpool: Oh, girl, you haven't lived until you do it while bodysliding.
Irene: (long silence)
Deadpool: Hmm... Let me rephrase. You haven't lived until you do it.
Irene: So... Cable is forced to... deal with you.
Deadpool: We bodyslide by one, yeah, sorta like a Play-Doh thing happening. We bodyslide by two and we appear side by side. Either way, we're hermanos en fuego.
Irene: Brothers on fire?
Deadpool: I thought it meant flaming brothers.
Irene: That's not much better.
"Cable and Deadpool did something with their bodies that's usually reserved for late-night cable T.V. As a result, when one bodyslides, or teleports, the other goes along for the ride. But that really has nothing to do with the story."
Once the introductions run out of one-night-stand jokes, they move on to guest appearances from the issue's secondary characters, all of whom are uncomfortable trying to define what type of relationship Cable and Deadpool have.
There is also how, after being restored from a partial lobotomy by Deadpool (with the mercenary's reasons for doing so also being ambiguously Ho-Yay at best) the first thing Cable does is ask Deadpool to keep talking, because he loves the sound of his voice.
Cable: No Wade... Don't shut up... your voice, that ridiculous hollow Demi Moore rumble... Is probably the sweetest sound I've ever heard.
To which Deadpool declares:
Deadpool: Nate?! I'm so in the mood to go to a broadway musical with you right now!
Also referenced by alternate reality Horsemen of Apocalypse Cable:
War/Cable: You have no idea Wade, how much I've missed that gravelly Demi Moore voice... Nor how much I regret having been the one who silenced it.
Deadpool and Weasel have a little bit of Ho Yay as well. Such as when Deadpool asserts that Weasel is "the perfect candidate for a nice, tight thong" when trying to convince him to take up the name Pool Boy and become Deadpool's official sidekick. The mention of Don't Ask, Don't Tell immediately after this comment does not help.
And Deadpool is in the habit of fanboying The Cat when they meet.
In an early issue of Deadpool's original solo series, Flatman appears to be hitting on Weasel a couple times. He offers Weasel a massage to make him feel better and calls him "sailor", which he tells Big Bertha is a term of endearment when she questions it.
Flatman has since outed himself as gay. This was probably just foreshadowing.
And then there's Bob of HYDRA, who's gone from hostage to unsure minion to adoring fanboy in the span of just a few issues. Seriously, what is it about Deadpool?
There's also the point that Bob has never, even early on, questioned or objected to being called Deadpool's pet.
Here is a not-complete list of... slashy panels from Cable & Deadpool.