Nick Cannon -- I Made Mariah Hit the High Notes !

Now we know what Nick Cannon was saying about in his new song referencing Mariah Carey ... He's actually talking about a text ... and not what it sounded like.

It sounded like he said "I got a check," referring to his soon-to-be ex-wife. But someone involved in the production tells us he says "text" and not "check."

Nick does brag he gets an A in the bedroom ... rapping he makes Mariah hit the high notes.

Nick, producer Mally Mall and rapper's French Montana and Too Short were at a Hollywood strip club Sunday shooting the video for the song, and we got Nick's verse on cam. So it's a little hard to make out, but here's what we think he says:

I'm a freak
It goes like this
Yo the freaks come out at night
I'm like Houdini with the magic stick when you turn out the lights
With this Girl names Keisha, Aphrodite
Ass so phat half black and white
Hit high notes n**** ask my wife
Whoops I mean ex, I got a text
Let's sex
I need a freak
Everyday on me
We all clean, we all clean

He's movin' on.