A joke which the Senior Student recounted at the ULAS Annual Dinner in (I think) 1971-ish!
Unfortunately, DWRAF was not very impressed. Very p*ssed off, in fact - as the Boss soon discovered! Particularly as the chap also told the one about measuring WRAFs for trousers... (Not the "Use a metre rule, take the wet from the dry and add 3" for the turnups" line, but one almost as bad!)