But now students at one university have been banned from throwing their mortar boards in the air at graduation ceremonies because of health and safety fears.
Bosses at Anglia Ruskin University say a student could be seriously injured by the corner of one of the square caps.
They say ending the tradition will also protect the mortar boards themselves from damage.
One student needed stitches a few years ago after he was hit on the head at a ceremony, according to the university, although there have been no other incidents. No legal action was taken.
Student union president Frankie Whiffen said: 'It sounds like health and safety gone mad.
'It's an important tradition and who is going to go round stopping it anyway - the hat police? ...
Laura Midgley, of the Campaign Against Political Correctness, said: 'The likelihood of being injured by a flying hat appears to be very low.
'The students are far more likely to be injured on their way to and from the ceremony - especially if they are travelling in cars which are known to kill thousands every year.
So with this logic, the whole ceremony should be cancelled.
Wow! The "Campaign Against Political Correctness!" How do I join and how do I set up a U.S. chapter?!