Hilary Duff Sings About Sexual Act in New Song

Hilary Duff is getting dirty on her upcoming album ... teasing a new song in which she sings about giving oral sex!

Check out her post from Wednesday -- the former Disney darling posted a video of herself lip-syncing to an unreleased song in which she sings about the NSFW act. The lyrics read ... "I want the part where you say goddamn / Back of a dive bar giving you head / Then sneak home late, wake up your roommates.”

But that's not where the risqué story ends -- later in the song, she croons ... "I’m touching myself by the front door / But you don’t even look my way no more." The overall song has her nostalgic about a once hot and heavy relationship that has faded into a passionless reflection of the relationship they once shared.

Hilary's sexy song tease came as she completely ignored the drama that erupted over Ashley Tisdale's recent essay for "The Cut," in which she wrote about a "toxic" mom group fans assumed included Hilary, Mandy Moore, and Meghan Trainor. In the essay, Ashley said she was once part of a group of moms who made her feel "hurt, drained or left out."

And while Ashley's rep told TMZ her essay had nothing to do with the online speculation ... Hilary's husband Matthew Koma seemingly stuck up for her by sharing a mocked-up photo that showed him posing for "The Cut" in the same pose Ashley was. The faux cover story's headline read ... "A mom group tell all through a father’s eyes: When You’re the Most Self-Obsessed Tone Deaf Person on Earth, Other Moms Tend to Shift Focus To Their Actual Toddlers."