Check out video ... Ye is seen lifting Bianca in the air while simultaneously planting his face directly in between her breasts -- which are at risk of popping out thanks to the 2 bits of cloth she's rocking as a top.

The PDA moment comes courtesy of additional footage from Bianca's untamed 30th birthday bash, which had a number of eyebrow-raising moments. (More on that later on!!!)

Bianca seems unbothered by the public motorboating ... she's seen laughing and smiling while clinging to the back of her rapper husband's head during the whole exchange.

Bianca and Kanye are cheered on by a number of partygoers, who joined the couple in the Maldives for BC's wild 30th birthday bash Sunday.

In different footage from the party celebrating her milestone, Kanye is filmed treating Bianca and her guests to a performance of his 2011 hit, "N****s in Paris." The Yeezy architect proves to be Kanye's No. 1 fan in the clip, too ... looking wild-eyed as she raps along to the popular track.

As fans haven't gotten many chances to hear Bianca speak -- let alone rap -- this moment is certainly one to make note of!!!

Kanye pulled out all the stops for his wife's big birthday. As TMZ previously reported, the rap mogul made a rare return to Instagram to share a tribute in Bianca's honor ... uploading a video of his wife in her literal birthday suit.

He then posted another video of Bianca ... where she appeared to grind up on none other than Oscar winner Penelope Cruz.