The "Insecure" creator and star addressed a new rumor circulating for the past week -- namely that Issa is expecting her first child. Now, this is based purely on a video of her where folks apparently thought they saw evidence she had a bun in the oven.

Welp, IR is finally weighing in, saying ... "I am not pregnant, f**kyouverymuch." For extra emphasis, she added ... "LET A BITCH EAT DRINK AND BE MERRY."

The clip in question was shot last Friday at the Kennedy Center in D.C., where she was hosting a festival touting Black creatives.

She was definitely in a celebratory mood -- dancing and embracing a friend -- and perhaps that spurred people to connect dots that weren't really there. Some commented her stomach seemed to be poppin' ... but those folks were dead wrong, and Issa's now put 'em in their place.

She did just marry her longtime BF, Louis Diame, last year ... so maybe people thought there was something to that as well.