It must have been on Monday 9th October 1978. The first thing our professor told us in his first lecture on 'the neurological basis of human behaviour' was that "reality was a state of mind brought about by low blood alcohol concentrations". He wasn't the first to say something like this; it is borrowed - and adapted somewhat - from N.F. Simpson. I tracked down the original quotation to him when I heard it used in an obituary after his death in 2011. The line appears in A Resounding Tinkle. (Reference can be found to it in Martin Esslin's 'The Theatre of the Absurd'.)
I suspect that everybody thought prof. very witty to come out with such an idea. He was somebody in whom we were all in awe. Few of us thought then that he might have 'borrowed' it from elsewhere. In lectures, he rarely, if ever, cited his sources. Once, in a dissecting class, a rather odd pelvic structure was discovered. The lecturer in charge hadn't seen anything like it before and asked somebody to go and get prof. to see if he knew what it was - adding somewhat wryly that even if he didn't know he would still come out with something that sounded definitive.