the use of @ and # before Twitter

Grawlixes, AKA obscenicons are the short strings of symbols that take the place of profanity. It seems positively quaint in today's world when just about everything is considered fit for print, though you may still see it on rare occasion. I was reminded of the device recently when I read The Pigman. (I checked it out of the library after seeing it among the books on display at the New York Public Library's The ABC of It: Why Children's Books Matter). 
The 1968 novel has two narrators, and the teen boy says that to abstain from using curse words, he will type  “@#$%” or“3@#$%.”  I'm not certain I've ever seen the use of grawlixes in books before, though I have seen the oblique reference, something along the lines of "He called her something I cannot repeat," that you can find in a book lie The Forsyte Sage  or the dashes following a letter like "d___ " that you can find in books by the Brontes.

I have the impression that language in print really loosened up in the 1990s, and this fits with what I found in a 2000 article about the shifting standard for newspapers: "He spent 10 years at the San Antonio Express-News, where he watched 'damn' go from being bleeped out to containing dashes to being fully spelled out. "
BTW If you want to hear grawlixes in a song, there is one here:

Related post http://writewaypro.blogspot.com/2013/08/blame-ship-logs-for-this-word.html