A beer.
"Britney poured herself a cold bottle of Britney from the fridge to cool off after the hot hike."
A female given name transferred from the place name, variant of Brittany.
"Britney is a popular female given name that originates as a variant of the place name Brittany."
The term is a piece of rhyming slang derived from singer Britney Spears that was adopted to refer to beer. It emerged as a playful nickname within British subcultures where the name rhymes with "beers."