This is not true. The Irish who lived and worked in the Caribbean from the 17th century on were, at worst, indentured servants not slaves. Myth was debunked by Liam Hogan and others.
It's a myth there were 'Irish slaves' in Barbados. As difficult as white servants' experiences were, enslaved Africans…www.thejournal.ie
In Ireland, we have many individuals who engage in our own version of the Oppression Olympics. For example, Ireland’s foremost comedian, Gerry Adams, tweeted in May that the lead character in the movie “Django Unchained” was a “Ballymurphy Niggar” (Adams grew up in a Ballymurphy estate in Belfast) and claimed that nationalists in Northern Ireland were as badly treated as African Americans.