Chrissy Teigen and John Legend got sweet and sticky on camera, and as a result ... they've scored a mountain of her fave candy.

Chrissy posted a video of herself enjoying Fun Dip and convincing John to suck it -- the Dip stick -- for the first time in his life. Of course, he loved it. It's pure sugar, after all.

Nestle spotted Chrissy's vid and seized the marketing opportunity ... sending out a Valentine's Day basket loaded with box after box after box of Fun Dip. We're told they even threw in a frog toy for baby Luna, and one other thing reserved for VIPs.

John and Chrissy are getting first crack at a brand new, not-yet-released flavor -- Mango Lime with Tamarind.

Dental costs not included.