The questionable comment is thought to have been made after Shaughna Phillips, 25, was dumped by Callum.
Heartbroken Shaughna was comforted by the girls after Callum arrived back from Casa Amor with new partner Molly.
As Rebecca told Shaughna she shouldn't date scaffolders any more, many fans thought they hear Siannise drop the N-word.
One fan wrote: "So I hope Love Island are investigating Siannise using the N word last night?! Because she definitely said it & we ain’t brushing it under no carpet!!"
Another added: "So siannise used the N word on love island bruv I’m black and I cannot even being myself to use it what is these white ppls obsessions with saying it?"
A third chipped in: "Did anyone hear siannese straight up say the n word on the latest ep of Love Island?"
A fourth fumed: "Someone said the N word and should be kicked off the show and apologise. It is unacceptable and I am no longer going to watch the show."
Fans think the ITV babe said: "Date n*****s" however, ITV have denied the claim.
Instead, ITV insisted Siannise had said: "They ain’t no good."
A rep for Love Island said: "Viewers are mistaken.
"No one said — and nor would we broadcast — the word in question. We strongly refute any suggestion to the contrary."
Earlier this week fans watched as Casa Amor tore the villa apart.
Shaughna was left heartbroken by Callum's decision to call time on their blossoming romance.
After Callum finally decided to pull her for a chat to discuss his decision, Shaughna said: "I think you would have known there was something missing before you went into Casa Amor, and you would have maybe spoken to me about that, but you never.
"Don’t insult me and try to say you’ve done me a favour. I don’t know how I’m going to live in this villa now with that.
"How am I not going to feel uncomfortable? This wasn’t just a coupling up for me, I genuinely had feelings for you.
"You’re with her now, and that’s that. It’s just a bit s**t for me."
Is Shaughna going to stay in the villa?
Love Island continues on ITV2 at 9pm