Harry Styles & Niall Horan Instagram Flirting? Taylor Swift's Ex Sexually Propositions One Direction Hottie, 'Can I Sit On Your Face Please?'

The boys of One Direction are well-known pranksters. And their fans love it! But did Harry Styles go a bit too far with this vulgar Instagram comment aimed at fellow bandmate Niall Horan?

Earlier this month, the blonde "Story Of My Life" cutie shared this goofy snapshot with fans:

niallhoran: "Oi oi!"

Several followers soon realized that Taylor Swift's ex commented on Horan's playful tongue pic:

harrystyles: "Can I sit on your face. Please?"

Okay, the 1D crooner's probably just joking. But still - ew!

Pretty frisky behavior for the 20-year-old pop star, whose fan-base is mostly made-up of preteen girls!

Do MstarsNews readers find Styles' "sexual proposition" rather inappropriate? Or is he actually sort of flirting!?

Well, several One Directioners did not approve. But others were totally turned-on. The epic selfie now has more than 130,000 comments and counting.

Meanwhile, rumors were recently debunked that Horan was shockingly leaving the band. An alleged insider tells HollywoodLife.com:

"Harry thought it would be funny if he had the whole band act like Niall was out of the band and started talking to him and treating him like he was in the past tense - they ran with it all day."

And now this...