I will pass over your subtle suggestion that I am a liar and simply state that the incident, in which I named the institution (an old-fashioned Poly that was formed I believe from a sports education college, with a strong rugby spirit and which had a reputation for hard drinking and hard playing) and when the incident happened, in the 1980s a time that was much less intolerant of such behaviour.Regardless of the veracity of that particular dit, this is a good point.
I will also point out that two other posters reported similar incidents at a rugby do and an Army initiation ritual, so why I should be cast as the liar and the others not, I have no idea. Meanwhile I will leave you these links to peruse (some relate to sports hazing in US colleges, it's not fanciful to believe that similar practices occur in the UK) to see if maybe you think they are lying too.
Why humiliating university initiations need to be stopped
SAGE Journals: Your gateway to world-class research journals
University of Surrey 'deeply saddened' by students' 'degrading initiation'
Rugby initiation ceremony saw 'bottle inserted in to player's anus'
The brutal secret of school sport initiations