Selena Gomez Licks Boyfriend Benny Blanco's Crotch on 'Open Wide' Cake

Selena Gomez seems really excited about her boyfriend Benny Blanco's new book, tucking into a tasty cake shaped just like it -- and going in tongue first, aiming below the belt.

The actress posted an interesting shot to her Instagram Tuesday -- showing her going down and licking a cake that was made to be a replica of Benny's cookbook, 'Open Wide' ... which just got released this week. The catch ... a picture of BB himself is on the cake.

The reason that's relevant is because the picture Selena posted -- and others that are circulating of this interesting moment -- shows her licking cake-Benny's crotch!

SG's tongue is out and licking the cake -- this while Benny and others look on. They also took a couple pics together, snuggled up in the snap and looked smitten. The two of them have been putting on a 24/7 lovefest since they first got together ... so more of the same.

As for this crotch lick -- it might come across as a bit much for some -- but honestly, it's more silly than sexual, and just a moment of Selena having a little NSFW fun with her BF.

Big picture, she's just celebrating the guy's milestone ... certainly something to be proud of.

As you probably know ... Benny has made a name for himself in showbiz as a music producer -- but these days, he's also making a splash on TikTok as a chef-style influencer.

He's constantly posting cooking videos -- and it actually plays a big role in his relationship with Selena. She's constantly posting reminders that he whips up meals for her regularly.

BTW ... Benny's cooking is apparently a turn-on for Selena  -- at least, according to Benny, anyway, who dropped a vid on social media where he claims he makes Gomez steak whenever he wants to get laid, implying it seems to work on her.