Do you mean a half and half?

"The term Black and Tan has a totally different connotation in Irish history. (fairly recent Irish history, at that) “Black and Tan” was the nickname given to the British paramilitary force “formed to suppress the Irish independence movement in 1920 and 1921.” They were mostly of ex-servicemen who’d served in World War I and they all wore khakis and dark shirts."

https://vinepair.com/wine-blog/why-you-should-never-order-a-black-and-tan-in-ireland/ 

 All true about how you order in Ireland, but there's a difference between a Half & Half and a Black & Tan:  

B&T usually means Guinness and Bass Ale, while H&H is Guinness and Harp.  H&H more common now, since we don't find Bass on tap in many places.