"Tell Me Something Good" (Rufus feat. Chaka Khan)

Time was, Stevie Wonder was bubbling over with so much unbridled creativity that, not only was he churning out his own awe-inspiring albums every few months, he was giving away a ton of music to other artists, too.  Aretha Franklin, The Spinners, and the band Rufus, to name but a few.
Wonder became a fan of Rufus after hearing their 1973 cover of his song "Maybe Your Baby," which features a searing lead vocal from Chaka Khan.  To express his admiration, he decided to write Rufus an original song with Khan's voice in mind.
So one afternoon, he surprised them by dropping by their recording studio in L.A. and unveiled his new composition, a funky, upbeat song called "Come and Get This Stuff."
Khan (being Khan) flat out told Wonder that she didn't care for it.
As you can imagine, the band was mortified.  But Wonder (being Wonder) laughed it off and whipped up the sultry "Tell Me Something Good" in response.  
(He ultimately gave "Come and Get This Stuff" to his ex-wife, Syreeta Wright, for her second album, Stevie Wonder Presents: Syreeta.)
Like every Wonder composition, everything on "Tell Me Something Good" from 1974's Rags to Rufus is in its right place: the slinky verses with their descending clavinet lines, the noteless bridges with their heavy-breathing vocal percussion, and the fiery choruses with their rapturous exclamations of Tell me something good, punctuated by "talkbox" and distorted lead guitars.  It all serves to make your hips move like...well...y'know.
But it's Khan's performance that seals the deal.  She promises that she's gonna set your stuff on fire, and then she delivers, tenfold.  Her vocal is so naughty yet so sublimely sweet, I'm sure it's why radio programmers in 1974 couldn't resist keeping this paean to good nookie in constant rotation.

"You Got the Love" (Chaka Khan & Rufus)

"You Got the Love" from Rags to Rufus (1974) is all about rhythm.  It seeps into your hips from the chicken-scratch guitar, fat gulps of bass, and just-behind-the-beat drums.  And if for some reason those don't get you to move, that searing lead guitar and Chaka Khan's sultry delivery will.
The song, which Khan wrote with Ray Parker, Jr. (as in Ghostbusters and Raydio), is about someone having such an irresistible hold on you that you can't help but give in to their charms.  But at the same time, you've got the same kind of hold on them.  (Those not-so-subtle growled I love ya's / I need ya's after Khan's verses are evidence of that.)
It's rare for the funk to get this romantic or for romance to get this funky.