Sir Ian McKellen tells Oxford students what will happen if they don't study for their exams (you can probably guess)

They'll be attacked by a Balrog apparently

(ambrosefullalove/Instagram)

Alongside partner in crime Sir Patrick Stewart, Sir Ian McKellen knows how to give fans what they want.

Be it delightful photo tours of New York or helping random fans propose, the actor is only too happy to indulge people and always has bags of energy.

As such, when he visited students at Oxford University this week he served up his most famous Lord of the Rings line unprompted.

"And you know what will happen [if you don't study]," he told an already giggling audience, "YOU SHALL NOT PAAAAASSSS!"

A video posted by Ambrose Fullalove (@ambrosefullalove) on Nov 11, 2014 at 2:16pm PST

His sonorous shout was met with cheering and whooping from the students; Sir Ian merely smiled serenely.

The actor's next film, The Hobbit: The Battle of the Five Armies, is currently in post-production, while he is rumoured to be featuring in an upcoming Noel Coward biopic.