A New York English professor taught a Starbucks barista a lesson because, she complained, she had been asked about what she wanted on her bagel in a grammatically incorrect way.

Lynne Rosenthal, an academic at Mercy College with a Phd from Columbia University, was forcibly removed form an Upper West Side branch of the coffee chain for allegedly calling the barista “an a***hole."

The 60-something had ordered a toasted multigrain bagel, but would not specify her non-choice of topping.

She was told: “You're not going to get anything unless you say butter or cheese!"

Dr Rosenthal told the New York Post: "I refused to say 'without butter or cheese.' When you go to Burger King, you don't have to list the six things you don't want.

“Linguistically, it's stupid, and I'm a stickler for correct English."

Dr Rosenthal, who makes a habit of describing her coffee orders as "small" or "large" rather than Starbuck’s description of "tall" or "venti ", began shouting at the barista when he wouldn’t budge.

She only left the shop when police arrived and threatened to arrest her – and she never did get her breakfast.

She added: “It was very humiliating to be thrown out, and all I did was ask for a bagel.”