I used to do CADD (Computer Aided Drafting and Design), and on many many CADD files there are humorous (and sometimes raunchy or disgruntled) comments or details, reduced by a factor of thousands or on an obscure layer, or as part of a fill pattern. AS I like my job I contented myself to put my initials as a fill element on an architectural detail, but I've seen some things from clients..... That this was all part of such an ancient tradition I did not know.
That is very interesting, thanks. I guess it's just people being people.