The title characters of The Ren & Stimpy Show are the spitting image of the stereotypical 1950s husband and wife, with Stimpy as the fussy housewife and Ren as the exasperated "working stiff", Ren delivering frequent Domestic Abuse to an absolutely submissive Stimpy (unless the episode required something different), and the both of them sleeping in the same bed.
This song is more than enough to know there's something going on, with lines like "I've never asked for anything, just your happiness" or "And just once, when you strike that pose, could you think of me?".
Despite the subject of Ren and Stimpy being more than friends appearing as a harmless joke in the original show, the Adult Party Cartoon series, though not official, explicitly confirmed it.
"Son of Stimpy": A distraught Stimpy is at the door calling for his "son" Stinky. Ren tries to get him inside to decorate the tree, then points up at the mistletoe hanging over the door, bites his lip and coyly bats his eyelashes. Stimpy screams "That's all you can THINK OF!" in response. Yeah, that's not even trying to hide it.
In this same episode, when Stimpy's "son" introduces his fiancÚ to Stimpy and Ren. They are holding each others, and sing "Memoriiiiiies".
The amount of times Stimpy orders Ren to open his mouth in that episode is highly disturbing. Granted he's Ren's nurse, but the mischevous/enthusiastic expressions he puts on while doing that encourages further implications (to those whose minds choose to go into the gutter). The medicine taking scene is really exaggerated, with making the spoon REALLY huge and Ren mentioning that "that's some icky-tasting stuff!" (had Ren mentioned that it was medicine, then it wouldn't have been so risque) and the countless Double Entendres ("Now, swallow every little drop! Isn't it tasty?").
It's more than implied that Stimpy is a Living Emotional Crutch to Ren. In the very first episode, Stimpy leaves Ren (temporarily). Ren falls to pieces within the first five minutes.
Not to mention Ren giving Stimpy a kiss on the lips in his sleep, while lustfully murmuring that they will exchange saliva. However, when he wakes up, he screams and goes to wash his mouth. Note that Stimpy was awake all the time, and eagerly kicks his foot in the air when Ren pets him and kisses him.
In "The Great Outdoors", Stimpy suggests skinny diving. Ren tells him that he's crazy, and Stimpy responds with "Come on, Ren, you'll like it" as he looks back at him slyly while taking off his skin. The looks Ren gives Stimpy just sells it.
Not to mention, Stimpy's over-enthusastic demand to Ren to take off his underwear. Ren refuses for a few moments, but eventually gives in, and goes into the lake. When he reaches Stimpy, the latter says "Well, hello there" in a very seductive manner. It's so blatant that you wonder if there were any shippers on the staff.
All of this was taken Up to Eleven in the "Adult Party Cartoon" version, with Ren forcing Stimpy to repeat "You're the pitcher, I'm the catcher!" several times in the very first episode of the reboot.